[v4,3/5] spi: spi-qpic: Add qpic spi nand driver support

Add qpic spi nand driver support. The spi nand
driver currently supported the below commands.

-- RESET
-- READ ID
-- SET FEATURE
-- GET FEATURE
-- READ PAGE
-- WRITE PAGE
-- ERASE PAGE

Co-developed-by: Sricharan Ramabadhran <quic_srichara@quicinc.com>
Signed-off-by: Sricharan Ramabadhran <quic_srichara@quicinc.com>
Co-developed-by: Varadarajan Narayanan <quic_varada@quicinc.com>
Signed-off-by: Varadarajan Narayanan <quic_varada@quicinc.com>
Signed-off-by: Md Sadre Alam <quic_mdalam@quicinc.com>
---
Change in [v4]

* No change

Change in [v3]

* Set SPI_QPIC_SNAND to n and added COMPILE_TEST in Kconfig

* Made driver name sorted in Make file

* Made comment like c++

* Changed macro to functions, snandc_set_read_loc_last()
  and snandc_set_read_loc_first()

* Added error handling in snandc_set_reg()

* Changed into normal conditional statement for
  return snandc->ecc_stats.failed ? -EBADMSG :
  snandc->ecc_stats.bitflips;

* Remove cast of wbuf in qpic_snand_program_execute()
  function

* Made num_cw variable instead hardcoded value

* changed if..else condition of function qpic_snand_io_op()
  to switch..case statement

* Added __devm_spi_alloc_controller() api instead of
  devm_spi_alloc_master()

* Disabling clock in remove path

Change in [v2]

* Added initial support for SPI-NAND driver

Change in [v1]

* Added RFC patch for design review

 drivers/mtd/nand/qpic_common.c       |    8 +
 drivers/spi/Kconfig                  |    8 +
 drivers/spi/Makefile                 |    1 +
 drivers/spi/spi-qpic-snand.c         | 1041 ++++++++++++++++++++++++++
 include/linux/mtd/nand-qpic-common.h |   61 ++
 5 files changed, 1119 insertions(+)
 create mode 100644 drivers/spi/spi-qpic-snand.c

Hi,

quic_mdalam@quicinc.com wrote on Fri,  8 Mar 2024 14:47:50 +0530:

> Add qpic spi nand driver support. The spi nand
> driver currently supported the below commands.
> 
> -- RESET
> -- READ ID
> -- SET FEATURE
> -- GET FEATURE
> -- READ PAGE
> -- WRITE PAGE
> -- ERASE PAGE
> 
> Co-developed-by: Sricharan Ramabadhran <quic_srichara@quicinc.com>
> Signed-off-by: Sricharan Ramabadhran <quic_srichara@quicinc.com>
> Co-developed-by: Varadarajan Narayanan <quic_varada@quicinc.com>
> Signed-off-by: Varadarajan Narayanan <quic_varada@quicinc.com>
> Signed-off-by: Md Sadre Alam <quic_mdalam@quicinc.com>

I don't like the "spi nand driver" wording here. It is a spi
controller, for spi-memories.

Plus, I'd expect some kind of check to see whether you support the
requested operation, I don't see any in the code.


> ---
> Change in [v4]
> 
> * No change
> 
> Change in [v3]
> 
> * Set SPI_QPIC_SNAND to n and added COMPILE_TEST in Kconfig
> 
> * Made driver name sorted in Make file
> 
> * Made comment like c++
> 
> * Changed macro to functions, snandc_set_read_loc_last()
>   and snandc_set_read_loc_first()
> 
> * Added error handling in snandc_set_reg()
> 
> * Changed into normal conditional statement for
>   return snandc->ecc_stats.failed ? -EBADMSG :
>   snandc->ecc_stats.bitflips;
> 
> * Remove cast of wbuf in qpic_snand_program_execute()
>   function
> 
> * Made num_cw variable instead hardcoded value
> 
> * changed if..else condition of function qpic_snand_io_op()
>   to switch..case statement
> 
> * Added __devm_spi_alloc_controller() api instead of
>   devm_spi_alloc_master()
> 
> * Disabling clock in remove path
> 
> Change in [v2]
> 
> * Added initial support for SPI-NAND driver
> 
> Change in [v1]
> 
> * Added RFC patch for design review
> 
>  drivers/mtd/nand/qpic_common.c       |    8 +
>  drivers/spi/Kconfig                  |    8 +
>  drivers/spi/Makefile                 |    1 +
>  drivers/spi/spi-qpic-snand.c         | 1041 ++++++++++++++++++++++++++
>  include/linux/mtd/nand-qpic-common.h |   61 ++
>  5 files changed, 1119 insertions(+)
>  create mode 100644 drivers/spi/spi-qpic-snand.c
> 
> diff --git a/drivers/mtd/nand/qpic_common.c b/drivers/mtd/nand/qpic_common.c
> index 5b7c0d119d9a..67ccb3d05f20 100644
> --- a/drivers/mtd/nand/qpic_common.c
> +++ b/drivers/mtd/nand/qpic_common.c
> @@ -134,6 +134,14 @@ __le32 *qcom_offset_to_nandc_reg(struct nandc_regs *regs, int offset)
>  		return &regs->read_location_last2;
>  	case NAND_READ_LOCATION_LAST_CW_3:
>  		return &regs->read_location_last3;
> +	case NAND_FLASH_SPI_CFG:
> +		return &regs->spi_cfg;
> +	case NAND_NUM_ADDR_CYCLES:
> +		return &regs->num_addr_cycle;
> +	case NAND_BUSY_CHECK_WAIT_CNT:
> +		return &regs->busy_wait_cnt;
> +	case NAND_FLASH_FEATURES:
> +		return &regs->flash_feature;

I am still not convinced about these. I don't understand who you have
this indirection.

>  	default:
>  		return NULL;
>  	}
> diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
> index bc7021da2fe9..63764e943d82 100644
> --- a/drivers/spi/Kconfig
> +++ b/drivers/spi/Kconfig
> @@ -882,6 +882,14 @@ config SPI_QCOM_QSPI
>  	help
>  	  QSPI(Quad SPI) driver for Qualcomm QSPI controller.
>  
> +config SPI_QPIC_SNAND
> +	tristate "QPIC SNAND controller"
> +	depends on ARCH_QCOM || COMPILE_TEST
> +	help
> +	  QPIC_SNAND (QPIC SPI NAND) driver for Qualcomm QPIC controller.
> +	  QPIC controller supports both parallel nand and serial nand.
> +	  This config will enable serial nand driver for QPIC controller.
> +
>  config SPI_QUP
>  	tristate "Qualcomm SPI controller with QUP interface"
>  	depends on ARCH_QCOM || COMPILE_TEST
> diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
> index 4ff8d725ba5e..9015368f8c73 100644
> --- a/drivers/spi/Makefile
> +++ b/drivers/spi/Makefile
> @@ -111,6 +111,7 @@ obj-$(CONFIG_SPI_PXA2XX)		+= spi-pxa2xx-platform.o
>  obj-$(CONFIG_SPI_PXA2XX_PCI)		+= spi-pxa2xx-pci.o
>  obj-$(CONFIG_SPI_QCOM_GENI)		+= spi-geni-qcom.o
>  obj-$(CONFIG_SPI_QCOM_QSPI)		+= spi-qcom-qspi.o
> +obj-$(CONFIG_SPI_QPIC_SNAND)            += spi-qpic-snand.o
>  obj-$(CONFIG_SPI_QUP)			+= spi-qup.o
>  obj-$(CONFIG_SPI_ROCKCHIP)		+= spi-rockchip.o
>  obj-$(CONFIG_SPI_ROCKCHIP_SFC)		+= spi-rockchip-sfc.o
> diff --git a/drivers/spi/spi-qpic-snand.c b/drivers/spi/spi-qpic-snand.c
> new file mode 100644
> index 000000000000..df7d5d8d4db2
> --- /dev/null
> +++ b/drivers/spi/spi-qpic-snand.c
> @@ -0,0 +1,1041 @@
> +/*
> + * SPDX-License-Identifier: GPL-2.0
> + *
> + * Copyright (c) 2023, Qualcomm Innovation Center, Inc. All rights reserved.
> + *
> + * Authors:
> + *	Md Sadre Alam <quic_mdalam@quicinc.com>
> + *	Sricharan R <quic_srichara@quicinc.com>
> + *	Varadarajan Narayanan <quic_varada@quicinc.com>
> + */
> +
> +#include <linux/mtd/spinand.h>
> +#include <linux/mtd/nand-qpic-common.h>
> +
> +/* QSPI NAND config reg bits */
> +#define LOAD_CLK_CNTR_INIT_EN   BIT(28)
> +#define CLK_CNTR_INIT_VAL_VEC   0x924
> +#define FEA_STATUS_DEV_ADDR     0xc0
> +#define SPI_CFG			BIT(0)
> +#define SPI_NUM_ADDR		0xDA4DB
> +#define SPI_WAIT_CNT		0x10
> +#define QPIC_QSPI_NUM_CS	1
> +#define SPI_TRANSFER_MODE_x1	BIT(29)
> +#define SPI_TRANSFER_MODE_x4	(3 << 29)
> +#define SPI_WP			BIT(28)
> +#define SPI_HOLD		BIT(27)
> +#define QPIC_SET_FEATURE	BIT(31)
> +
> +#define SPINAND_RESET		0xff
> +#define SPINAND_READID		0x9f
> +#define SPINAND_GET_FEATURE	0x0f
> +#define SPINAND_SET_FEATURE	0x1f
> +#define SPINAND_READ		0x13
> +#define SPINAND_ERASE		0xd8
> +#define SPINAND_WRITE_EN	0x06
> +#define SPINAND_PROGRAM_EXECUTE	0x10
> +#define SPINAND_PROGRAM_LOAD	0x84
> +
> +struct qpic_snand_op {
> +	u32 cmd_reg;
> +	u32 addr1_reg;
> +	u32 addr2_reg;
> +};
> +
> +struct snandc_read_status {
> +	__le32 snandc_flash;
> +	__le32 snandc_buffer;
> +	__le32 snandc_erased_cw;
> +};
> +
> +static void snandc_set_reg(struct qcom_nand_controller *snandc, int offset, u32 val)

qcom_spi_ would be a better prefix maybe?

> +{
> +	struct nandc_regs *regs = snandc->regs;
> +	__le32 *reg;
> +
> +	reg = qcom_offset_to_nandc_reg(regs, offset);
> +
> +	if (reg)
> +		*reg = cpu_to_le32(val);
> +
> +	if (WARN_ON(!reg))
> +		return;

This whole logic really seems suboptimal. 

> +}
> +
> +static void snandc_set_read_loc_first(struct qcom_nand_controller *snandc,
> +				      int reg, int cw_offset, int read_size,
> +				      int is_last_read_loc)
> +{
> +	snandc_set_reg(snandc, reg, ((cw_offset) << READ_LOCATION_OFFSET) |
> +		       ((read_size) << READ_LOCATION_SIZE) | ((is_last_read_loc)
> +			       << READ_LOCATION_LAST));

FIELD_GET, FIELD_PREP ?

> +}
> +
> +static void snandc_set_read_loc_last(struct qcom_nand_controller *snandc,
> +				     int reg, int cw_offset, int read_size,
> +				     int is_last_read_loc)
> +{
> +	snandc_set_reg(snandc, reg, ((cw_offset) << READ_LOCATION_OFFSET) |
> +		       ((read_size) << READ_LOCATION_SIZE) | ((is_last_read_loc)
> +			       << READ_LOCATION_LAST));
> +}
> +
> +static struct qcom_nand_controller *nand_to_qcom_snand(struct nand_device *nand)
> +{
> +	struct nand_ecc_engine *eng = nand->ecc.engine;
> +
> +	return container_of(eng, struct qcom_nand_controller, ecc_eng);
> +}
> +
> +static int qcom_snand_init(struct qcom_nand_controller *snandc)
> +{
> +	u32 snand_cfg_val = 0x0;
> +	int ret;
> +
> +	snand_cfg_val |= (LOAD_CLK_CNTR_INIT_EN | (CLK_CNTR_INIT_VAL_VEC << 16)
> +			| (FEA_STATUS_DEV_ADDR << 8) | SPI_CFG);

                        ^
the | should be on the previous line.

> +
> +	snandc_set_reg(snandc, NAND_FLASH_SPI_CFG, 0);
> +	snandc_set_reg(snandc, NAND_FLASH_SPI_CFG, snand_cfg_val);
> +	snandc_set_reg(snandc, NAND_NUM_ADDR_CYCLES, SPI_NUM_ADDR);
> +	snandc_set_reg(snandc, NAND_BUSY_CHECK_WAIT_CNT, SPI_WAIT_CNT);
> +
> +	qcom_write_reg_dma(snandc, NAND_FLASH_SPI_CFG, 1, 0);
> +	qcom_write_reg_dma(snandc, NAND_FLASH_SPI_CFG, 1, 0);
> +
> +	snand_cfg_val &= ~LOAD_CLK_CNTR_INIT_EN;
> +	snandc_set_reg(snandc, NAND_FLASH_SPI_CFG, snand_cfg_val);
> +
> +	qcom_write_reg_dma(snandc, NAND_FLASH_SPI_CFG, 1, 0);
> +
> +	qcom_write_reg_dma(snandc, NAND_NUM_ADDR_CYCLES, 1, 0);
> +	qcom_write_reg_dma(snandc, NAND_BUSY_CHECK_WAIT_CNT, 1, NAND_BAM_NEXT_SGL);
> +
> +	ret = qcom_submit_descs(snandc);
> +	if (ret)
> +		dev_err(snandc->dev, "failure in sbumitting spiinit descriptor\n");

Typos...

> +
> +	return 0;

return ret ?

> +}
> +
> +static int qcom_snand_ooblayout_ecc(struct mtd_info *mtd, int section,
> +				    struct mtd_oob_region *oobregion)
> +{
> +	struct nand_device *nand = mtd_to_nanddev(mtd);
> +	struct qcom_nand_controller *snandc = nand_to_qcom_snand(nand);
> +	struct qpic_ecc *qecc = snandc->ecc;
> +
> +	if (section > 1)
> +		return -ERANGE;
> +
> +	if (!section) {
> +		oobregion->length = (qecc->bytes * (qecc->steps - 1)) + qecc->bbm_size;
> +		oobregion->offset = 0;

No BBM?

> +	} else {
> +		oobregion->length = qecc->ecc_bytes_hw + qecc->spare_bytes;
> +		oobregion->offset = mtd->oobsize - oobregion->length;
> +	}
> +
> +	return 0;
> +}
> +
> +static int qcom_snand_ooblayout_free(struct mtd_info *mtd, int section,
> +				     struct mtd_oob_region *oobregion)
> +{
> +	struct nand_device *nand = mtd_to_nanddev(mtd);
> +	struct qcom_nand_controller *snandc = nand_to_qcom_snand(nand);
> +	struct qpic_ecc *qecc = snandc->ecc;
> +
> +	if (section)
> +		return -ERANGE;
> +
> +	oobregion->length = qecc->steps * 4;
> +	oobregion->offset = ((qecc->steps - 1) * qecc->bytes) + qecc->bbm_size;
> +

Using the same order would be easier to compare with the above version

> +	return 0;
> +}
> +
> +static const struct mtd_ooblayout_ops qcom_snand_ooblayout = {
> +	.ecc = qcom_snand_ooblayout_ecc,
> +	.free = qcom_snand_ooblayout_free,
> +};
> +
> +static int qpic_snand_ecc_init_ctx_pipelined(struct nand_device *nand)
> +{
> +	struct qcom_nand_controller *snandc = nand_to_qcom_snand(nand);
> +	struct nand_ecc_props *conf = &nand->ecc.ctx.conf;
> +	struct nand_ecc_props *reqs = &nand->ecc.requirements;
> +	struct nand_ecc_props *user = &nand->ecc.user_conf;
> +	struct mtd_info *mtd = nanddev_to_mtd(nand);
> +	int step_size = 0, strength = 0, steps;
> +	int cwperpage, bad_block_byte;
> +	struct qpic_ecc *ecc_cfg;
> +
> +	cwperpage = mtd->writesize / NANDC_STEP_SIZE;
> +	snandc->num_cw = cwperpage;
> +
> +	ecc_cfg = kzalloc(sizeof(*ecc_cfg), GFP_KERNEL);
> +	if (!ecc_cfg)
> +		return -ENOMEM;
> +
> +	nand->ecc.ctx.priv = ecc_cfg;
> +
> +	if (user->step_size && user->strength) {
> +		step_size = user->step_size;
> +		strength = user->strength;
> +	} else if (reqs->step_size && reqs->strength) {
> +		step_size = reqs->step_size;
> +		strength = reqs->strength;
> +	}
> +
> +	if (step_size && strength)
> +		steps = mtd->writesize / step_size;
> +
> +	ecc_cfg->ecc_bytes_hw = 7;
> +	ecc_cfg->spare_bytes = 4;
> +	ecc_cfg->bbm_size = 1;
> +	ecc_cfg->bch_enabled = true;
> +	ecc_cfg->bytes = ecc_cfg->ecc_bytes_hw + ecc_cfg->spare_bytes + ecc_cfg->bbm_size;
> +
> +	ecc_cfg->steps = 4;
> +	ecc_cfg->strength = 4;
> +	ecc_cfg->step_size = 512;
> +
> +	mtd_set_ooblayout(mtd, &qcom_snand_ooblayout);
> +
> +	ecc_cfg->cw_data = 516;
> +	ecc_cfg->cw_size = ecc_cfg->cw_data + ecc_cfg->bytes;
> +	bad_block_byte = mtd->writesize - ecc_cfg->cw_size * (cwperpage - 1) + 1;
> +
> +	ecc_cfg->cfg0 = (cwperpage - 1) << CW_PER_PAGE
> +				| ecc_cfg->cw_data << UD_SIZE_BYTES
> +				| 1 << DISABLE_STATUS_AFTER_WRITE
> +				| 3 << NUM_ADDR_CYCLES
> +				| ecc_cfg->ecc_bytes_hw << ECC_PARITY_SIZE_BYTES_RS
> +				| 0 << STATUS_BFR_READ
> +				| 1 << SET_RD_MODE_AFTER_STATUS
> +				| ecc_cfg->spare_bytes << SPARE_SIZE_BYTES;
> +
> +	ecc_cfg->cfg1 = 0 << NAND_RECOVERY_CYCLES
> +				| 0 <<  CS_ACTIVE_BSY
> +				| bad_block_byte << BAD_BLOCK_BYTE_NUM
> +				| 0 << BAD_BLOCK_IN_SPARE_AREA
> +				| 20 << WR_RD_BSY_GAP
> +				| 0 << WIDE_FLASH
> +				| ecc_cfg->bch_enabled << ENABLE_BCH_ECC;
> +
> +	ecc_cfg->cfg0_raw = (cwperpage - 1) << CW_PER_PAGE
> +				| ecc_cfg->cw_size << UD_SIZE_BYTES
> +				| 3 << NUM_ADDR_CYCLES
> +				| 0 << SPARE_SIZE_BYTES;
> +
> +	ecc_cfg->cfg1_raw = 0 << NAND_RECOVERY_CYCLES
> +				| 0 << CS_ACTIVE_BSY
> +				| 17 << BAD_BLOCK_BYTE_NUM
> +				| 1 << BAD_BLOCK_IN_SPARE_AREA
> +				| 20 << WR_RD_BSY_GAP
> +				| 0 << WIDE_FLASH
> +				| 1 << DEV0_CFG1_ECC_DISABLE;
> +
> +	ecc_cfg->ecc_bch_cfg = !ecc_cfg->bch_enabled << ECC_CFG_ECC_DISABLE
> +				| 0 << ECC_SW_RESET
> +				| ecc_cfg->cw_data << ECC_NUM_DATA_BYTES
> +				| 1 << ECC_FORCE_CLK_OPEN
> +				| 0 << ECC_MODE
> +				| ecc_cfg->ecc_bytes_hw << ECC_PARITY_SIZE_BYTES_BCH;
> +
> +	ecc_cfg->ecc_buf_cfg = 0x203 << NUM_STEPS;
> +	ecc_cfg->clrflashstatus = FS_READY_BSY_N;
> +	ecc_cfg->clrreadstatus = 0xc0;
> +
> +	conf->step_size = ecc_cfg->step_size;
> +	conf->strength = ecc_cfg->strength;
> +
> +	if (ecc_cfg->strength < strength)
> +		dev_warn(snandc->dev, "Unable to fulfill ECC requirements of %u bits.\n", strength);

Not needed I guess. Somewhat redundant with the core?

> +
> +	dev_info(snandc->dev, "ECC strength: %u bits per %u bytes\n",
> +		 ecc_cfg->strength, ecc_cfg->step_size);

Debug?

> +
> +	return 0;
> +}
> +
> +static void qpic_snand_ecc_cleanup_ctx_pipelined(struct nand_device *nand)
> +{
> +	struct qpic_ecc *ecc_cfg = nand_to_ecc_ctx(nand);
> +
> +	kfree(ecc_cfg);
> +}
> +
> +static int qpic_snand_ecc_prepare_io_req_pipelined(struct nand_device *nand,
> +						   struct nand_page_io_req *req)
> +{
> +	struct qcom_nand_controller *snandc = nand_to_qcom_snand(nand);
> +	struct qpic_ecc *ecc_cfg = nand_to_ecc_ctx(nand);
> +
> +	snandc->ecc = ecc_cfg;
> +	snandc->raw = false;
> +	snandc->oob_read = false;
> +
> +	if (req->mode == MTD_OPS_RAW) {
> +		if (req->ooblen)
> +			snandc->oob_read = true;
> +		snandc->raw = true;
> +	}
> +
> +	return 0;
> +}
> +
> +static int qpic_snand_ecc_finish_io_req_pipelined(struct nand_device *nand,
> +						  struct nand_page_io_req *req)
> +{
> +	struct qcom_nand_controller *snandc = nand_to_qcom_snand(nand);
> +	struct mtd_info *mtd = nanddev_to_mtd(nand);
> +
> +	if (req->mode == MTD_OPS_RAW || req->type != NAND_PAGE_READ)
> +		return 0;
> +
> +	if (snandc->ecc_stats.failed)
> +		mtd->ecc_stats.failed += snandc->ecc_stats.failed;
> +	mtd->ecc_stats.corrected += snandc->ecc_stats.corrected;
> +
> +	if (snandc->ecc_stats.failed)

I hope you reset this counter at some point.

Did you run nandbiterrs -i ?

> +		return -EBADMSG;
> +	else
> +		return snandc->ecc_stats.bitflips;
> +}
> +
> +static struct nand_ecc_engine_ops qcom_snand_ecc_engine_ops_pipelined = {
> +	.init_ctx = qpic_snand_ecc_init_ctx_pipelined,
> +	.cleanup_ctx = qpic_snand_ecc_cleanup_ctx_pipelined,
> +	.prepare_io_req = qpic_snand_ecc_prepare_io_req_pipelined,
> +	.finish_io_req = qpic_snand_ecc_finish_io_req_pipelined,
> +};
> +
> +/* helper to configure location register values */
> +static void snandc_set_read_loc(struct qcom_nand_controller *snandc, int cw, int reg,
> +				int cw_offset, int read_size, int is_last_read_loc)
> +{
> +	int reg_base = NAND_READ_LOCATION_0;
> +
> +	if (cw == 3)
> +		reg_base = NAND_READ_LOCATION_LAST_CW_0;
> +
> +	reg_base += reg * 4;
> +
> +	if (cw == 3)
> +		return snandc_set_read_loc_last(snandc, reg_base, cw_offset,
> +				read_size, is_last_read_loc);

Alignments are still wrong, again.

> +	else
> +		return snandc_set_read_loc_first(snandc, reg_base, cw_offset,
> +				read_size, is_last_read_loc);
> +}
> +
> +static void
> +snandc_config_cw_read(struct qcom_nand_controller *snandc, bool use_ecc, int cw)
> +{
> +	int reg = NAND_READ_LOCATION_0;
> +
> +	if (cw == 3)
> +		reg = NAND_READ_LOCATION_LAST_CW_0;
> +
> +	if (snandc->props->is_bam)
> +		qcom_write_reg_dma(snandc, reg, 4, NAND_BAM_NEXT_SGL);
> +
> +	qcom_write_reg_dma(snandc, NAND_FLASH_CMD, 1, NAND_BAM_NEXT_SGL);
> +	qcom_write_reg_dma(snandc, NAND_EXEC_CMD, 1, NAND_BAM_NEXT_SGL);
> +
> +	qcom_read_reg_dma(snandc, NAND_FLASH_STATUS, 2, 0);
> +	qcom_read_reg_dma(snandc, NAND_ERASED_CW_DETECT_STATUS, 1,
> +			  NAND_BAM_NEXT_SGL);
> +}
> +
> +static int qpic_snand_block_erase(struct qcom_nand_controller *snandc)
> +{
> +	struct qpic_ecc *ecc_cfg = snandc->ecc;
> +	int ret;
> +
> +	snandc->buf_count = 0;
> +	snandc->buf_start = 0;
> +	qcom_clear_read_regs(snandc);
> +	qcom_clear_bam_transaction(snandc);
> +
> +	snandc_set_reg(snandc, NAND_FLASH_CMD, snandc->cmd);
> +	snandc_set_reg(snandc, NAND_ADDR0, snandc->addr1);
> +	snandc_set_reg(snandc, NAND_ADDR1, snandc->addr2);
> +	snandc_set_reg(snandc, NAND_DEV0_CFG0, ecc_cfg->cfg0_raw & ~(7 << CW_PER_PAGE));
> +	snandc_set_reg(snandc, NAND_DEV0_CFG1, ecc_cfg->cfg1_raw);
> +	snandc_set_reg(snandc, NAND_EXEC_CMD, 1);
> +
> +	qcom_write_reg_dma(snandc, NAND_FLASH_CMD, 3, NAND_BAM_NEXT_SGL);
> +	qcom_write_reg_dma(snandc, NAND_DEV0_CFG0, 2, NAND_BAM_NEXT_SGL);
> +	qcom_write_reg_dma(snandc, NAND_EXEC_CMD, 1, NAND_BAM_NEXT_SGL);
> +
> +	ret = qcom_submit_descs(snandc);
> +	if (ret) {
> +		dev_err(snandc->dev, "failure to erase block\n");
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static void config_snand_single_cw_page_read(struct qcom_nand_controller *snandc,
> +					     bool use_ecc, int cw)
> +{
> +	int reg;
> +
> +	qcom_write_reg_dma(snandc, NAND_ADDR0, 2, 0);
> +	qcom_write_reg_dma(snandc, NAND_DEV0_CFG0, 3, 0);
> +	qcom_write_reg_dma(snandc, NAND_ERASED_CW_DETECT_CFG, 1, 0);
> +	qcom_write_reg_dma(snandc, NAND_ERASED_CW_DETECT_CFG, 1,
> +			   NAND_ERASED_CW_SET | NAND_BAM_NEXT_SGL);
> +
> +	reg = NAND_READ_LOCATION_0;
> +	if (cw == 3)

This is hardcoded everywhere, I am not a big fan.

> +		reg = NAND_READ_LOCATION_LAST_CW_0;
> +	qcom_write_reg_dma(snandc, reg, 4, NAND_BAM_NEXT_SGL);
> +	qcom_write_reg_dma(snandc, NAND_FLASH_CMD, 1, NAND_BAM_NEXT_SGL);
> +	qcom_write_reg_dma(snandc, NAND_EXEC_CMD, 1, NAND_BAM_NEXT_SGL);
> +
> +	qcom_read_reg_dma(snandc, NAND_FLASH_STATUS, 2, 0);
> +	qcom_read_reg_dma(snandc, NAND_ERASED_CW_DETECT_STATUS, 1, NAND_BAM_NEXT_SGL);
> +}
> +
> +static int qpic_snand_read_oob(struct qcom_nand_controller *snandc,
> +			       const struct spi_mem_op *op)
> +{
> +	struct qpic_ecc *ecc_cfg = snandc->ecc;
> +	int size, ret;
> +	int col,  bbpos;
> +	u32 cfg0, cfg1, ecc_bch_cfg;
> +	u32 num_cw = snandc->num_cw;
> +
> +	qcom_clear_bam_transaction(snandc);
> +	qcom_clear_read_regs(snandc);
> +
> +	size = ecc_cfg->cw_size;
> +	col = ecc_cfg->cw_size * (num_cw - 1);
> +
> +	/* prepare a clean read buffer */
> +	memset(snandc->data_buffer, 0xff, size);
> +	snandc_set_reg(snandc, NAND_ADDR0, (snandc->addr1 | col));
> +	snandc_set_reg(snandc, NAND_ADDR1, snandc->addr2);
> +
> +	cfg0 = (ecc_cfg->cfg0_raw & ~(7U << CW_PER_PAGE)) |
> +		0 << CW_PER_PAGE;
> +	cfg1 = ecc_cfg->cfg1_raw;
> +	ecc_bch_cfg = 1 << ECC_CFG_ECC_DISABLE;
> +
> +	snandc_set_reg(snandc, NAND_FLASH_CMD, snandc->cmd);
> +	snandc_set_reg(snandc, NAND_DEV0_CFG0, cfg0);
> +	snandc_set_reg(snandc, NAND_DEV0_CFG1, cfg1);
> +	snandc_set_reg(snandc, NAND_DEV0_ECC_CFG, ecc_bch_cfg);
> +	snandc_set_reg(snandc, NAND_EXEC_CMD, 1);
> +
> +	config_snand_single_cw_page_read(snandc, false, num_cw - 1);
> +
> +	qcom_read_data_dma(snandc, FLASH_BUF_ACC, snandc->data_buffer, size, 0);
> +
> +	ret = qcom_submit_descs(snandc);
> +	if (ret)
> +		dev_err(snandc->dev, "failed to read oob\n");

Why don't you return here?

> +
> +	qcom_nandc_read_buffer_sync(snandc, true);
> +	u32 flash = le32_to_cpu(snandc->reg_read_buf[0]);

No compiler warning here?

> +
> +	if (flash & (FS_OP_ERR | FS_MPU_ERR))
> +		return -EIO;
> +
> +	bbpos = 2048 - ecc_cfg->cw_size * (num_cw - 1);

Why is this size hardcoded?! That cannot work!

> +	memcpy(op->data.buf.in, snandc->data_buffer + bbpos, op->data.nbytes);
> +
> +	return ret;
> +}
> +
> +static int snandc_check_error(struct qcom_nand_controller *snandc)
> +{
> +	struct snandc_read_status *buf;
> +	int i, num_cw = snandc->num_cw;
> +	bool serial_op_err = false, erased;
> +
> +	qcom_nandc_read_buffer_sync(snandc, true);
> +	buf = (struct snandc_read_status *)snandc->reg_read_buf;
> +
> +	for (i = 0; i < num_cw; i++, buf++) {
> +		u32 flash, buffer, erased_cw;
> +
> +		flash = le32_to_cpu(buf->snandc_flash);
> +		buffer = le32_to_cpu(buf->snandc_buffer);
> +		erased_cw = le32_to_cpu(buf->snandc_erased_cw);
> +
> +		if ((flash & FS_OP_ERR) && (buffer & BS_UNCORRECTABLE_BIT)) {
> +			erased = (erased_cw & ERASED_CW) == ERASED_CW ?
> +				true : false;

This ternary operation is useless

> +		} else if (flash & (FS_OP_ERR | FS_MPU_ERR)) {
> +			serial_op_err = true;
> +		}
> +	}
> +
> +	if (serial_op_err)
> +		return -EIO;
> +
> +	return 0;
> +}
> +
> +static int qpic_snand_read_page_cache(struct qcom_nand_controller *snandc,
> +				      const struct spi_mem_op *op)
> +{
> +	struct qpic_ecc *ecc_cfg = snandc->ecc;
> +	u8 *data_buf;
> +	int ret, i;
> +	u32 cfg0, cfg1, ecc_bch_cfg, num_cw = snandc->num_cw;
> +
> +	data_buf = op->data.buf.in;
> +
> +	if (snandc->oob_read) {
> +		return qpic_snand_read_oob(snandc, op);
> +		snandc->oob_read = false;
> +	}
> +
> +	snandc->buf_count = 0;
> +	snandc->buf_start = 0;
> +	qcom_clear_read_regs(snandc);
> +
> +	cfg0 = (ecc_cfg->cfg0 & ~(7U << CW_PER_PAGE)) |
> +				(num_cw - 1) << CW_PER_PAGE;
> +	cfg1 = ecc_cfg->cfg1;
> +	ecc_bch_cfg = ecc_cfg->ecc_bch_cfg;
> +
> +	snandc_set_reg(snandc, NAND_ADDR0, snandc->addr1);
> +	snandc_set_reg(snandc, NAND_ADDR1, snandc->addr2);
> +	snandc_set_reg(snandc, NAND_FLASH_CMD, snandc->cmd);
> +	snandc_set_reg(snandc, NAND_DEV0_CFG0, cfg0);
> +	snandc_set_reg(snandc, NAND_DEV0_CFG1, cfg1);
> +	snandc_set_reg(snandc, NAND_DEV0_ECC_CFG, ecc_bch_cfg);
> +	snandc_set_reg(snandc, NAND_FLASH_STATUS, ecc_cfg->clrflashstatus);
> +	snandc_set_reg(snandc, NAND_READ_STATUS, ecc_cfg->clrreadstatus);
> +	snandc_set_reg(snandc, NAND_EXEC_CMD, 1);
> +	snandc_set_read_loc(snandc, 0, 0, 0, ecc_cfg->cw_data, 1);
> +
> +	qcom_clear_bam_transaction(snandc);
> +
> +	qcom_write_reg_dma(snandc, NAND_ADDR0, 2, 0);
> +	qcom_write_reg_dma(snandc, NAND_DEV0_CFG0, 3, 0);
> +	qcom_write_reg_dma(snandc, NAND_ERASED_CW_DETECT_CFG, 1, 0);
> +	qcom_write_reg_dma(snandc, NAND_ERASED_CW_DETECT_CFG, 1,
> +			   NAND_ERASED_CW_SET | NAND_BAM_NEXT_SGL);
> +
> +	for (i = 0; i < num_cw; i++) {
> +		int data_size;
> +
> +		if (i == (num_cw - 1))
> +			data_size = 512 - ((num_cw - 1) << 2);
> +		else
> +			data_size = ecc_cfg->cw_data;
> +
> +		if (data_buf)
> +			snandc_set_read_loc(snandc, i, 0, 0, data_size, 1);
> +
> +		snandc_config_cw_read(snandc, true, i);
> +
> +		if (data_buf)
> +			qcom_read_data_dma(snandc, FLASH_BUF_ACC, data_buf,
> +					   data_size, 0);
> +
> +		if (data_buf)
> +			data_buf += data_size;
> +	}
> +
> +	ret = qcom_submit_descs(snandc);
> +	if (ret) {
> +		dev_err(snandc->dev, "failure to read page/oob\n");
> +		return ret;
> +	}
> +
> +	return snandc_check_error(snandc);
> +}
> +
> +static void config_snand_page_write(struct qcom_nand_controller *snandc)
> +{
> +	qcom_write_reg_dma(snandc, NAND_ADDR0, 2, 0);
> +	qcom_write_reg_dma(snandc, NAND_DEV0_CFG0, 3, 0);
> +	qcom_write_reg_dma(snandc, NAND_EBI2_ECC_BUF_CFG, 1, NAND_BAM_NEXT_SGL);
> +}
> +
> +static void config_snand_cw_write(struct qcom_nand_controller *snandc)
> +{
> +	qcom_write_reg_dma(snandc, NAND_FLASH_CMD, 1, NAND_BAM_NEXT_SGL);
> +	qcom_write_reg_dma(snandc, NAND_EXEC_CMD, 1, NAND_BAM_NEXT_SGL);
> +}
> +
> +static int qpic_snand_program_execute(struct qcom_nand_controller *snandc,
> +				      const struct spi_mem_op *op)
> +{
> +	struct qpic_ecc *ecc_cfg = snandc->ecc;
> +	u8 *data_buf;
> +	int i, ret;
> +	int num_cw = snandc->num_cw;
> +	u32 cfg0, cfg1, ecc_bch_cfg, ecc_buf_cfg;
> +
> +	cfg0 = (ecc_cfg->cfg0 & ~(7U << CW_PER_PAGE)) |
> +				(num_cw - 1) << CW_PER_PAGE;
> +	cfg1 = ecc_cfg->cfg1;
> +	ecc_bch_cfg = ecc_cfg->ecc_bch_cfg;
> +	ecc_buf_cfg = ecc_cfg->ecc_buf_cfg;
> +
> +	data_buf = snandc->wbuf;
> +
> +	snandc->buf_count = 0;
> +	snandc->buf_start = 0;
> +	qcom_clear_read_regs(snandc);
> +	qcom_clear_bam_transaction(snandc);
> +
> +	snandc_set_reg(snandc, NAND_ADDR0, snandc->addr1);
> +	snandc_set_reg(snandc, NAND_ADDR1, snandc->addr2);
> +	snandc_set_reg(snandc, NAND_FLASH_CMD, snandc->cmd);
> +
> +	snandc_set_reg(snandc, NAND_DEV0_CFG0, cfg0);
> +	snandc_set_reg(snandc, NAND_DEV0_CFG1, cfg1);
> +	snandc_set_reg(snandc, NAND_DEV0_ECC_CFG, ecc_bch_cfg);
> +
> +	snandc_set_reg(snandc, NAND_EBI2_ECC_BUF_CFG, ecc_buf_cfg);
> +
> +	snandc_set_reg(snandc, NAND_EXEC_CMD, 1);
> +
> +	config_snand_page_write(snandc);
> +
> +	for (i = 0; i < num_cw; i++) {
> +		int data_size;
> +
> +		if (i == (num_cw - 1))
> +			data_size = NANDC_STEP_SIZE - ((num_cw - 1) << 2);
> +		else
> +			data_size = ecc_cfg->cw_data;
> +
> +		qcom_write_data_dma(snandc, FLASH_BUF_ACC, data_buf, data_size,
> +				    i == (num_cw - 1) ? NAND_BAM_NO_EOT : 0);
> +
> +		config_snand_cw_write(snandc);
> +		if (data_buf)
> +			data_buf += data_size;
> +	}
> +
> +	ret = qcom_submit_descs(snandc);
> +	if (ret) {
> +		dev_err(snandc->dev, "failure to write page\n");
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static u32 qpic_snand_cmd_mapping(struct qcom_nand_controller *snandc, u32 opcode)
> +{
> +	u32 cmd = 0x0;
> +
> +	switch (opcode) {
> +	case SPINAND_RESET:
> +		cmd = (SPI_WP | SPI_HOLD | SPI_TRANSFER_MODE_x1 | OP_RESET_DEVICE);
> +		break;
> +	case SPINAND_READID:
> +		cmd = (SPI_WP | SPI_HOLD | SPI_TRANSFER_MODE_x1 | OP_FETCH_ID);
> +		break;
> +	case SPINAND_GET_FEATURE:
> +		cmd = (SPI_TRANSFER_MODE_x1 | SPI_WP | SPI_HOLD | ACC_FEATURE);
> +		break;
> +	case SPINAND_SET_FEATURE:
> +		cmd = (SPI_TRANSFER_MODE_x1 | SPI_WP | SPI_HOLD | ACC_FEATURE |
> +			QPIC_SET_FEATURE);
> +		break;
> +	case SPINAND_READ:
> +		if (snandc->raw)
> +			cmd = (PAGE_ACC | LAST_PAGE | SPI_TRANSFER_MODE_x1 |
> +					SPI_WP | SPI_HOLD | OP_PAGE_READ);
> +		else
> +			cmd = (PAGE_ACC | LAST_PAGE | SPI_TRANSFER_MODE_x1 |
> +					SPI_WP | SPI_HOLD | OP_PAGE_READ_WITH_ECC);
> +		break;
> +	case SPINAND_ERASE:
> +		cmd = OP_BLOCK_ERASE | PAGE_ACC | LAST_PAGE | SPI_WP |
> +			SPI_HOLD | SPI_TRANSFER_MODE_x1;
> +		break;
> +	case SPINAND_WRITE_EN:
> +		cmd = SPINAND_WRITE_EN;
> +		break;
> +	case SPINAND_PROGRAM_EXECUTE:
> +		cmd = (PAGE_ACC | LAST_PAGE | SPI_TRANSFER_MODE_x1 |
> +				SPI_WP | SPI_HOLD | OP_PROGRAM_PAGE);
> +		break;
> +	case SPINAND_PROGRAM_LOAD:
> +		cmd = SPINAND_PROGRAM_LOAD;
> +		break;
> +	default:
> +		break;

No, no, no and no again. You've been sending NAND contributions for
years, and you still continue to assume all the commands are defined
and we will never check for supported ops. Please.

> +	}
> +
> +	return cmd;
> +}
> +
> +static int qpic_snand_write_page_cache(struct qcom_nand_controller *snandc,
> +				       const struct spi_mem_op *op)
> +{
> +	struct qpic_snand_op s_op = {};
> +	u32 cmd;
> +
> +	cmd = qpic_snand_cmd_mapping(snandc, op->cmd.opcode);
> +	s_op.cmd_reg = cmd;
> +
> +	if (op->cmd.opcode == SPINAND_PROGRAM_LOAD) {
> +		snandc->wbuf = (u8 *)op->data.buf.out;
> +		snandc->wlen = op->data.nbytes;
> +	}
> +
> +	return 0;
> +}
> +
> +static int qpic_snand_send_cmdaddr(struct qcom_nand_controller *snandc,
> +				   const struct spi_mem_op *op)
> +{
> +	struct qpic_snand_op s_op = {};
> +	u32 cmd;
> +	int ret;
> +
> +	cmd = qpic_snand_cmd_mapping(snandc, op->cmd.opcode);
> +
> +	s_op.cmd_reg = cmd;
> +	s_op.addr1_reg = op->addr.val;
> +	s_op.addr2_reg = 0;
> +
Would a switch case be more appropriate?

> +	if (op->cmd.opcode == SPINAND_WRITE_EN)
> +		return 0;
> +
> +	if (op->cmd.opcode == SPINAND_PROGRAM_EXECUTE) {
> +		s_op.addr1_reg = op->addr.val << 16;
> +		s_op.addr2_reg = op->addr.val >> 16 & 0xff;
> +		snandc->addr1 = s_op.addr1_reg;
> +		snandc->addr2 = s_op.addr2_reg;
> +		snandc->cmd = cmd;
> +		return qpic_snand_program_execute(snandc, op);
> +	}
> +
> +	if (op->cmd.opcode == SPINAND_READ) {
> +		s_op.addr1_reg = (op->addr.val << 16);
> +		s_op.addr2_reg = op->addr.val >> 16 & 0xff;
> +		snandc->addr1 = s_op.addr1_reg;
> +		snandc->addr2 = s_op.addr2_reg;
> +		snandc->cmd = cmd;
> +		return 0;
> +	}
> +
> +	if (op->cmd.opcode == SPINAND_ERASE) {
> +		s_op.addr2_reg = (op->addr.val >> 16) & 0xffff;
> +		s_op.addr1_reg = op->addr.val;
> +		snandc->addr1 = s_op.addr1_reg;
> +		snandc->addr1 <<= 16;
> +		snandc->addr2 = s_op.addr2_reg;
> +		snandc->cmd = cmd;
> +		qpic_snand_block_erase(snandc);
> +		return 0;
> +	}
> +
> +	snandc->buf_count = 0;
> +	snandc->buf_start = 0;
> +	qcom_clear_read_regs(snandc);
> +	qcom_clear_bam_transaction(snandc);
> +
> +	snandc_set_reg(snandc, NAND_FLASH_CMD, s_op.cmd_reg);
> +	snandc_set_reg(snandc, NAND_EXEC_CMD, 0x1);
> +	snandc_set_reg(snandc, NAND_ADDR0, s_op.addr1_reg);
> +	snandc_set_reg(snandc, NAND_ADDR1, s_op.addr2_reg);
> +
> +	qcom_write_reg_dma(snandc, NAND_FLASH_CMD, 3, NAND_BAM_NEXT_SGL);
> +	qcom_write_reg_dma(snandc, NAND_EXEC_CMD, 1, NAND_BAM_NEXT_SGL);
> +
> +	ret = qcom_submit_descs(snandc);
> +	if (ret)
> +		dev_err(snandc->dev, "failure in sbumitting cmd descriptor\n");
> +
> +	return ret;
> +}
> +
> +static int qpic_snand_io_op(struct qcom_nand_controller *snandc, const struct spi_mem_op *op)
> +{
> +	int ret, val, opcode;
> +	bool copy = false, copy_ftr = false;
> +
> +	ret = qpic_snand_send_cmdaddr(snandc, op);
> +	if (ret)
> +		return ret;
> +
> +	snandc->buf_count = 0;
> +	snandc->buf_start = 0;
> +	qcom_clear_read_regs(snandc);
> +	qcom_clear_bam_transaction(snandc);
> +	opcode = op->cmd.opcode;
> +
> +	switch (opcode) {
> +	case SPINAND_READID:
> +		snandc->buf_count = 4;
> +		qcom_read_reg_dma(snandc, NAND_READ_ID, 1, NAND_BAM_NEXT_SGL);
> +		copy = true;
> +		break;
> +	case SPINAND_GET_FEATURE:
> +		snandc->buf_count = 4;
> +		qcom_read_reg_dma(snandc, NAND_FLASH_FEATURES, 1, NAND_BAM_NEXT_SGL);
> +		copy_ftr = true;
> +		break;
> +	case SPINAND_SET_FEATURE:
> +		snandc_set_reg(snandc, NAND_FLASH_FEATURES, *(u32 *)op->data.buf.out);
> +		qcom_write_reg_dma(snandc, NAND_FLASH_FEATURES, 1, NAND_BAM_NEXT_SGL);
> +		break;
> +	default:
> +		return 0;
> +	}
> +
> +	ret = qcom_submit_descs(snandc);
> +	if (ret)
> +		dev_err(snandc->dev, "failure in submitting descriptor for:%d\n", opcode);
> +
> +	if (copy) {
> +		qcom_nandc_read_buffer_sync(snandc, true);
> +		memcpy(op->data.buf.in, snandc->reg_read_buf, snandc->buf_count);
> +	}
> +
> +	if (copy_ftr) {
> +		qcom_nandc_read_buffer_sync(snandc, true);
> +		val = le32_to_cpu(*(__le32 *)snandc->reg_read_buf);
> +		val >>= 8;
> +		memcpy(op->data.buf.in, &val, snandc->buf_count);
> +	}
> +
> +	return ret;
> +}
> +
> +static bool qpic_snand_is_page_op(const struct spi_mem_op *op)
> +{
> +	if (op->addr.buswidth != 1 && op->addr.buswidth != 2 && op->addr.buswidth != 4)
> +		return false;
> +
> +	if (op->data.dir == SPI_MEM_DATA_IN) {
> +		if (op->addr.buswidth == 4 && op->data.buswidth == 4)
> +			return true;
> +
> +		if (op->addr.nbytes == 2 && op->addr.buswidth == 1)
> +			return true;
> +
> +	} else if (op->data.dir == SPI_MEM_DATA_OUT) {
> +		if (op->data.buswidth == 4)
> +			return true;
> +		if (op->addr.nbytes == 2 && op->addr.buswidth == 1)
> +			return true;
> +	}
> +
> +	return false;
> +}
> +
> +static bool qpic_snand_supports_op(struct spi_mem *mem, const struct spi_mem_op *op)
> +{
> +	if (!spi_mem_default_supports_op(mem, op))
> +		return false;
> +
> +	if (op->cmd.nbytes != 1 || op->cmd.buswidth != 1)
> +		return false;
> +
> +	if (qpic_snand_is_page_op(op))
> +		return true;
> +
> +	return ((op->addr.nbytes == 0 || op->addr.buswidth == 1) &&

		!op->addr.nbytes and so on

> +		(op->dummy.nbytes == 0 || op->dummy.buswidth == 1) &&
> +		(op->data.nbytes == 0 || op->data.buswidth == 1));
> +}
> +
> +static int qpic_snand_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
> +{
> +	struct qcom_nand_controller *snandc = spi_controller_get_devdata(mem->spi->controller);
> +
> +	dev_dbg(snandc->dev, "OP %02x ADDR %08llX@%d:%u DATA %d:%u", op->cmd.opcode,
> +		op->addr.val, op->addr.buswidth, op->addr.nbytes,
> +		op->data.buswidth, op->data.nbytes);
> +
> +	if (qpic_snand_is_page_op(op)) {
> +		if (op->data.dir == SPI_MEM_DATA_IN)
> +			return qpic_snand_read_page_cache(snandc, op);
> +		if (op->data.dir == SPI_MEM_DATA_OUT)
> +			return qpic_snand_write_page_cache(snandc, op);
> +	} else {
> +		return qpic_snand_io_op(snandc, op);
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct spi_controller_mem_ops qcom_spi_mem_ops = {
> +	.supports_op = qpic_snand_supports_op,
> +	.exec_op = qpic_snand_exec_op,
> +};
> +
> +static const struct spi_controller_mem_caps qcom_snand_mem_caps = {
> +	.ecc = true,
> +};
> +
> +static int qcom_snand_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct spi_controller *ctlr;
> +	struct qcom_nand_controller *snandc;
> +	struct resource *res;
> +	const void *dev_data;
> +	struct qpic_ecc *ecc;
> +	int ret;
> +
> +	ecc = devm_kzalloc(dev, sizeof(*ecc), GFP_KERNEL);
> +	if (!ecc)
> +		return -ENOMEM;
> +
> +	ctlr = __devm_spi_alloc_controller(dev, sizeof(*snandc), false);

I don't know if that is legitimate, why using __devm?

> +	if (!ctlr)
> +		return -ENOMEM;
> +
> +	platform_set_drvdata(pdev, ctlr);
> +
> +	snandc = spi_controller_get_devdata(ctlr);
> +
> +	snandc->ctlr = ctlr;
> +	snandc->dev = dev;
> +	snandc->ecc = ecc;
> +
> +	dev_data = of_device_get_match_data(dev);
> +	if (!dev_data) {
> +		dev_err(&pdev->dev, "failed to get device data\n");
> +		return -ENODEV;
> +	}
> +
> +	snandc->props = dev_data;
> +	snandc->dev = &pdev->dev;
> +
> +	snandc->core_clk = devm_clk_get(dev, "core");
> +	if (IS_ERR(snandc->core_clk))
> +		return PTR_ERR(snandc->core_clk);
> +
> +	snandc->aon_clk = devm_clk_get(dev, "aon");
> +	if (IS_ERR(snandc->aon_clk))
> +		return PTR_ERR(snandc->aon_clk);
> +
> +	snandc->iomacro_clk = devm_clk_get(dev, "iom");
> +	if (IS_ERR(snandc->iomacro_clk))
> +		return PTR_ERR(snandc->iomacro_clk);
> +
> +	snandc->base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
> +	if (IS_ERR(snandc->base))
> +		return PTR_ERR(snandc->base);
> +
> +	snandc->base_phys = res->start;
> +	snandc->base_dma = dma_map_resource(dev, res->start, resource_size(res),
> +					    DMA_BIDIRECTIONAL, 0);
> +	if (dma_mapping_error(dev, snandc->base_dma))
> +		return -ENXIO;
> +
> +	ret = clk_prepare_enable(snandc->core_clk);
> +	if (ret)
> +		goto err_core_clk;
> +
> +	ret = clk_prepare_enable(snandc->aon_clk);
> +	if (ret)
> +		goto err_aon_clk;
> +
> +	ret = clk_prepare_enable(snandc->iomacro_clk);
> +	if (ret)
> +		goto err_snandc_alloc;
> +
> +	ret = qcom_nandc_alloc(snandc);
> +	if (ret)
> +		goto err_snandc_alloc;
> +
> +	ret = qcom_snand_init(snandc);
> +	if (ret)
> +		goto err_init;
> +
> +	/* setup ECC engine */
> +	snandc->ecc_eng.dev = &pdev->dev;
> +	snandc->ecc_eng.integration = NAND_ECC_ENGINE_INTEGRATION_PIPELINED;
> +	snandc->ecc_eng.ops = &qcom_snand_ecc_engine_ops_pipelined;
> +	snandc->ecc_eng.priv = snandc;
> +
> +	ret = nand_ecc_register_on_host_hw_engine(&snandc->ecc_eng);
> +	if (ret) {
> +		dev_err(&pdev->dev, "failed to register ecc engine.\n");
> +		goto err_init;
> +	}
> +
> +	ctlr->num_chipselect = QPIC_QSPI_NUM_CS;
> +	ctlr->mem_ops = &qcom_spi_mem_ops;
> +	ctlr->mem_caps = &qcom_snand_mem_caps;
> +	ctlr->dev.of_node = pdev->dev.of_node;
> +	ctlr->mode_bits = SPI_TX_DUAL | SPI_RX_DUAL |
> +			    SPI_TX_QUAD | SPI_RX_QUAD;
> +
> +	ret = spi_register_controller(ctlr);
> +	if (ret) {
> +		dev_err(&pdev->dev, "spi_register_controller failed.\n");
> +		goto err_init;
> +	}
> +
> +	return 0;
> +
> +err_init:
> +	qcom_nandc_unalloc(snandc);
> +err_snandc_alloc:
> +	clk_disable_unprepare(snandc->aon_clk);
> +err_aon_clk:
> +	clk_disable_unprepare(snandc->core_clk);

Don't you miss one clock ?

> +err_core_clk:
> +	dma_unmap_resource(dev, res->start, resource_size(res),
> +			   DMA_BIDIRECTIONAL, 0);
> +	return ret;
> +}
> +
> +static int qcom_snand_remove(struct platform_device *pdev)
> +{
> +	struct spi_controller *ctlr = platform_get_drvdata(pdev);
> +	struct qcom_nand_controller *snandc = spi_controller_get_devdata(ctlr);
> +	struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +
> +	spi_unregister_controller(ctlr);
> +
> +	clk_disable_unprepare(snandc->aon_clk);
> +	clk_disable_unprepare(snandc->core_clk);
> +	clk_disable_unprepare(snandc->iomacro_clk);
> +
> +	dma_unmap_resource(&pdev->dev, snandc->base_dma, resource_size(res),
> +			   DMA_BIDIRECTIONAL, 0);
> +	return 0;
> +}
> +
> +static const struct qcom_nandc_props ipq9574_snandc_props = {
> +	.dev_cmd_reg_start = 0x7000,
> +	.is_bam = true,

Same comment about "is_bam"

> +};
> +
> +static const struct of_device_id qcom_snandc_of_match[] = {
> +	{
> +		.compatible = "qcom,spi-qpic-snand",
> +		.data = &ipq9574_snandc_props,
> +	},
> +	{}
> +}
> +MODULE_DEVICE_TABLE(of, qcom_snandc_of_match);
> +
> +static struct platform_driver qcom_snand_driver = {
> +	.driver = {
> +		.name		= "qcom_snand",
> +		.of_match_table = qcom_snandc_of_match,
> +	},
> +	.probe = qcom_snand_probe,
> +	.remove = qcom_snand_remove,
> +};
> +module_platform_driver(qcom_snand_driver);
> +
> +MODULE_DESCRIPTION("SPI driver for QPIC QSPI cores");
> +MODULE_AUTHOR("Md Sadre Alam <quic_mdalam@quicinc.com>");
> +MODULE_LICENSE("GPL");
> diff --git a/include/linux/mtd/nand-qpic-common.h b/include/linux/mtd/nand-qpic-common.h
> index aced15866627..4673cd36ff0a 100644
> --- a/include/linux/mtd/nand-qpic-common.h
> +++ b/include/linux/mtd/nand-qpic-common.h
> @@ -45,6 +45,9 @@
>  #define	NAND_DEV_CMD1			0xa4
>  #define	NAND_DEV_CMD2			0xa8
>  #define	NAND_DEV_CMD_VLD		0xac
> +#define NAND_FLASH_SPI_CFG              0xc0
> +#define NAND_NUM_ADDR_CYCLES            0xc4
> +#define NAND_BUSY_CHECK_WAIT_CNT        0xc8

If this is specific to the spi-nand implementation, then it's not
common and has no reason to be shared here. Same for the other
definitions of course.

>  #define	SFLASHC_BURST_CFG		0xe0
>  #define	NAND_ERASED_CW_DETECT_CFG	0xe8
>  #define	NAND_ERASED_CW_DETECT_STATUS	0xec
> @@ -61,6 +64,7 @@
>  #define	NAND_READ_LOCATION_LAST_CW_1	0xf44
>  #define	NAND_READ_LOCATION_LAST_CW_2	0xf48
>  #define	NAND_READ_LOCATION_LAST_CW_3	0xf4c
> +#define NAND_FLASH_FEATURES             0xf64
>  
>  /* dummy register offsets, used by write_reg_dma */
>  #define	NAND_DEV_CMD1_RESTORE		0xdead
> @@ -169,6 +173,7 @@
>  #define	OP_CHECK_STATUS			0xc
>  #define	OP_FETCH_ID			0xb
>  #define	OP_RESET_DEVICE			0xd
> +#define ACC_FEATURE                     0xe
>  
>  /* Default Value for NAND_DEV_CMD_VLD */
>  #define NAND_DEV_CMD_VLD_VAL		(READ_START_VLD | WRITE_START_VLD | \
> @@ -329,11 +334,53 @@ struct nandc_regs {
>  	__le32 read_location_last1;
>  	__le32 read_location_last2;
>  	__le32 read_location_last3;
> +	__le32 spi_cfg;
> +	__le32 num_addr_cycle;
> +	__le32 busy_wait_cnt;
> +	__le32 flash_feature;
>  
>  	__le32 erased_cw_detect_cfg_clr;
>  	__le32 erased_cw_detect_cfg_set;
>  };
>  
> +struct qcom_ecc_stats {
> +	u32 corrected;
> +	u32 bitflips;
> +	u32 failed;
> +};
> +
> +/*
> + * QPIC ECC data struct
> + *
> + */
> +struct qpic_ecc {
> +	struct device *dev;
> +	const struct qpic_ecc_caps *caps;
> +	struct completion done;
> +	u32 sectors;
> +	u8 *eccdata;
> +	bool use_ecc;
> +	u32 ecc_modes;
> +	int ecc_bytes_hw;
> +	int spare_bytes;
> +	int bbm_size;
> +	int ecc_mode;
> +	int bytes;
> +	int steps;
> +	int step_size;
> +	int strength;
> +	int cw_size;
> +	int cw_data;
> +	u32 cfg0, cfg1;
> +	u32 cfg0_raw, cfg1_raw;
> +	u32 ecc_buf_cfg;
> +	u32 ecc_bch_cfg;
> +	u32 clrflashstatus;
> +	u32 clrreadstatus;
> +	bool bch_enabled;
> +};
> +
> +struct qpic_ecc;
>  /*
>   * NAND controller data struct
>   *
> @@ -352,6 +399,7 @@ struct nandc_regs {
>   *				initialized via DT match data
>   *
>   * @controller:			base controller structure
> + * @ctlr:			spi controller structure
>   * @host_list:			list containing all the chips attached to the
>   *				controller
>   *
> @@ -389,6 +437,7 @@ struct qcom_nand_controller {
>  
>  	struct clk *core_clk;
>  	struct clk *aon_clk;
> +	struct clk *iomacro_clk;
>  
>  	struct nandc_regs *regs;
>  	struct bam_transaction *bam_txn;
> @@ -396,6 +445,7 @@ struct qcom_nand_controller {
>  	const struct qcom_nandc_props *props;
>  
>  	struct nand_controller controller;
> +	struct spi_controller *ctlr;
>  	struct list_head host_list;
>  
>  	union {
> @@ -432,6 +482,17 @@ struct qcom_nand_controller {
>  
>  	u32 cmd1, vld;
>  	bool exec_opwrite;
> +	struct qpic_ecc *ecc;
> +	struct qcom_ecc_stats ecc_stats;
> +	struct nand_ecc_engine ecc_eng;
> +	u8 *wbuf;
> +	u32 wlen;
> +	u32 addr1;
> +	u32 addr2;
> +	u32 cmd;
> +	u32 num_cw;
> +	bool oob_read;
> +	bool raw;
>  };
>  
>  /*


Thanks,
Miquèl

On 3/8/24 03:17, Md Sadre Alam wrote:
> Add qpic spi nand driver support. The spi nand
> driver currently supported the below commands.
> 
> -- RESET
> -- READ ID
> -- SET FEATURE
> -- GET FEATURE
> -- READ PAGE
> -- WRITE PAGE
> -- ERASE PAGE
> 
> Co-developed-by: Sricharan Ramabadhran <quic_srichara@quicinc.com>
> Signed-off-by: Sricharan Ramabadhran <quic_srichara@quicinc.com>
> Co-developed-by: Varadarajan Narayanan <quic_varada@quicinc.com>
> Signed-off-by: Varadarajan Narayanan <quic_varada@quicinc.com>
> Signed-off-by: Md Sadre Alam <quic_mdalam@quicinc.com>
> ---

For the entire series:

Tested-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>

> diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
> index bc7021da2fe9..63764e943d82 100644
> --- a/drivers/spi/Kconfig
> +++ b/drivers/spi/Kconfig
> @@ -882,6 +882,14 @@ config SPI_QCOM_QSPI
>   	help
>   	  QSPI(Quad SPI) driver for Qualcomm QSPI controller.
>   
> +config SPI_QPIC_SNAND
> +	tristate "QPIC SNAND controller"
> +	depends on ARCH_QCOM || COMPILE_TEST

Here, it needs to 'select QPIC_COMMON`. Otherwise it can run into 
unresolved symbols:

: drivers/spi/spi-qpic-snand.o: in function `snandc_set_reg':
  drivers/spi/spi-qpic-snand.c:56:(.text+0x484): undefined reference to 
`qcom_offset_to_nandc_reg'
...

> +	help
> +	  QPIC_SNAND (QPIC SPI NAND) driver for Qualcomm QPIC controller.
> +	  QPIC controller supports both parallel nand and serial nand.
> +	  This config will enable serial nand driver for QPIC controller.
> +
>   config SPI_QUP
>   	tristate "Qualcomm SPI controller with QUP interface"
>   	depends on ARCH_QCOM || COMPILE_TEST

Alex

On 4/7/24 12:48, Alex G. wrote:
> On 3/8/24 03:17, Md Sadre Alam wrote:
>> Add qpic spi nand driver support. The spi nand
>> driver currently supported the below commands.
>>
>> -- RESET
>> -- READ ID
>> -- SET FEATURE
>> -- GET FEATURE
>> -- READ PAGE
>> -- WRITE PAGE
>> -- ERASE PAGE
>>
>> Co-developed-by: Sricharan Ramabadhran <quic_srichara@quicinc.com>
>> Signed-off-by: Sricharan Ramabadhran <quic_srichara@quicinc.com>
>> Co-developed-by: Varadarajan Narayanan <quic_varada@quicinc.com>
>> Signed-off-by: Varadarajan Narayanan <quic_varada@quicinc.com>
>> Signed-off-by: Md Sadre Alam <quic_mdalam@quicinc.com>
>> ---
> 
> For the entire series:
> 
> Tested-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
> 
>> diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
>> index bc7021da2fe9..63764e943d82 100644
>> --- a/drivers/spi/Kconfig
>> +++ b/drivers/spi/Kconfig
>> @@ -882,6 +882,14 @@ config SPI_QCOM_QSPI
>>       help
>>         QSPI(Quad SPI) driver for Qualcomm QSPI controller.
>> +config SPI_QPIC_SNAND
>> +    tristate "QPIC SNAND controller"

Also, don't tristate this. It can be set as CONFIG_QPIC_COMMON=m, which 
will cause the build to fail because you don't have a MODULE_LICENSE().

>> +    depends on ARCH_QCOM || COMPILE_TEST
> 
> Here, it needs to 'select QPIC_COMMON`. Otherwise it can run into 
> unresolved symbols:
> 
> : drivers/spi/spi-qpic-snand.o: in function `snandc_set_reg':
>   drivers/spi/spi-qpic-snand.c:56:(.text+0x484): undefined reference to 
> `qcom_offset_to_nandc_reg'
> ...
> 
>> +    help
>> +      QPIC_SNAND (QPIC SPI NAND) driver for Qualcomm QPIC controller.
>> +      QPIC controller supports both parallel nand and serial nand.
>> +      This config will enable serial nand driver for QPIC controller.
>> +
>>   config SPI_QUP
>>       tristate "Qualcomm SPI controller with QUP interface"
>>       depends on ARCH_QCOM || COMPILE_TEST
> 
> Alex
Alex

On 4/7/24 13:40, Alex G. wrote:
> 
> 
> On 4/7/24 12:48, Alex G. wrote:
>> On 3/8/24 03:17, Md Sadre Alam wrote:
>>> Add qpic spi nand driver support. The spi nand
>>> driver currently supported the below commands.
>>>
>>> -- RESET
>>> -- READ ID
>>> -- SET FEATURE
>>> -- GET FEATURE
>>> -- READ PAGE
>>> -- WRITE PAGE
>>> -- ERASE PAGE
>>>
>>> Co-developed-by: Sricharan Ramabadhran <quic_srichara@quicinc.com>
>>> Signed-off-by: Sricharan Ramabadhran <quic_srichara@quicinc.com>
>>> Co-developed-by: Varadarajan Narayanan <quic_varada@quicinc.com>
>>> Signed-off-by: Varadarajan Narayanan <quic_varada@quicinc.com>
>>> Signed-off-by: Md Sadre Alam <quic_mdalam@quicinc.com>
>>> ---
>>
>> For the entire series:
>>
>> Tested-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
>>
>>> diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
>>> index bc7021da2fe9..63764e943d82 100644
>>> --- a/drivers/spi/Kconfig
>>> +++ b/drivers/spi/Kconfig
>>> @@ -882,6 +882,14 @@ config SPI_QCOM_QSPI
>>>       help
>>>         QSPI(Quad SPI) driver for Qualcomm QSPI controller.
>>> +config SPI_QPIC_SNAND
>>> +    tristate "QPIC SNAND controller"
> 
> Also, don't tristate this. It can be set as CONFIG_QPIC_COMMON=m, which 
> will cause the build to fail because you don't have a MODULE_LICENSE().

Please disregard my idiotic suggestion here. I meant to make this 
comment on the previous patch.

>>> +    depends on ARCH_QCOM || COMPILE_TEST
>>
>> Here, it needs to 'select QPIC_COMMON`. Otherwise it can run into 
>> unresolved symbols:
>>
>> : drivers/spi/spi-qpic-snand.o: in function `snandc_set_reg':
>>   drivers/spi/spi-qpic-snand.c:56:(.text+0x484): undefined reference 
>> to `qcom_offset_to_nandc_reg'
>> ...
>>
>>> +    help
>>> +      QPIC_SNAND (QPIC SPI NAND) driver for Qualcomm QPIC controller.
>>> +      QPIC controller supports both parallel nand and serial nand.
>>> +      This config will enable serial nand driver for QPIC controller.
>>> +
>>>   config SPI_QUP
>>>       tristate "Qualcomm SPI controller with QUP interface"
>>>       depends on ARCH_QCOM || COMPILE_TEST
>>
>> Alex
> Alex

On 07/04/2024 19:48, Alex G. wrote:
> On 3/8/24 03:17, Md Sadre Alam wrote:
>> Add qpic spi nand driver support. The spi nand
>> driver currently supported the below commands.
>>
>> -- RESET
>> -- READ ID
>> -- SET FEATURE
>> -- GET FEATURE
>> -- READ PAGE
>> -- WRITE PAGE
>> -- ERASE PAGE
>>
>> Co-developed-by: Sricharan Ramabadhran <quic_srichara@quicinc.com>
>> Signed-off-by: Sricharan Ramabadhran <quic_srichara@quicinc.com>
>> Co-developed-by: Varadarajan Narayanan <quic_varada@quicinc.com>
>> Signed-off-by: Varadarajan Narayanan <quic_varada@quicinc.com>
>> Signed-off-by: Md Sadre Alam <quic_mdalam@quicinc.com>
>> ---
> 
> For the entire series:
> 
> Tested-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
> 
>> diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
>> index bc7021da2fe9..63764e943d82 100644
>> --- a/drivers/spi/Kconfig
>> +++ b/drivers/spi/Kconfig
>> @@ -882,6 +882,14 @@ config SPI_QCOM_QSPI
>>   	help
>>   	  QSPI(Quad SPI) driver for Qualcomm QSPI controller.
>>   
>> +config SPI_QPIC_SNAND
>> +	tristate "QPIC SNAND controller"
>> +	depends on ARCH_QCOM || COMPILE_TEST
> 
> Here, it needs to 'select QPIC_COMMON`. Otherwise it can run into 
> unresolved symbols:
> 
> : drivers/spi/spi-qpic-snand.o: in function `snandc_set_reg':
>   drivers/spi/spi-qpic-snand.c:56:(.text+0x484): undefined reference to 
> `qcom_offset_to_nandc_reg'

No, do not select user-visible symbols. If you observe such issues then
either stubs are missing or depends on.

Best regards,
Krzysztof

On 07/04/2024 20:45, Alex G. wrote:
> 
> 
> On 4/7/24 13:40, Alex G. wrote:
>>
>>
>> On 4/7/24 12:48, Alex G. wrote:
>>> On 3/8/24 03:17, Md Sadre Alam wrote:
>>>> Add qpic spi nand driver support. The spi nand
>>>> driver currently supported the below commands.
>>>>
>>>> -- RESET
>>>> -- READ ID
>>>> -- SET FEATURE
>>>> -- GET FEATURE
>>>> -- READ PAGE
>>>> -- WRITE PAGE
>>>> -- ERASE PAGE
>>>>
>>>> Co-developed-by: Sricharan Ramabadhran <quic_srichara@quicinc.com>
>>>> Signed-off-by: Sricharan Ramabadhran <quic_srichara@quicinc.com>
>>>> Co-developed-by: Varadarajan Narayanan <quic_varada@quicinc.com>
>>>> Signed-off-by: Varadarajan Narayanan <quic_varada@quicinc.com>
>>>> Signed-off-by: Md Sadre Alam <quic_mdalam@quicinc.com>
>>>> ---
>>>
>>> For the entire series:
>>>
>>> Tested-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
>>>
>>>> diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
>>>> index bc7021da2fe9..63764e943d82 100644
>>>> --- a/drivers/spi/Kconfig
>>>> +++ b/drivers/spi/Kconfig
>>>> @@ -882,6 +882,14 @@ config SPI_QCOM_QSPI
>>>>       help
>>>>         QSPI(Quad SPI) driver for Qualcomm QSPI controller.
>>>> +config SPI_QPIC_SNAND
>>>> +    tristate "QPIC SNAND controller"
>>
>> Also, don't tristate this. It can be set as CONFIG_QPIC_COMMON=m, which 
>> will cause the build to fail because you don't have a MODULE_LICENSE().
> 
> Please disregard my idiotic suggestion here. I meant to make this 
> comment on the previous patch.
> 

Also not. All of these must be allowed to be a module. If you need
dependency between modules, then use documented syntax in the kernel
(foo || !foo).

Best regards,
Krzysztof

On 4/7/24 13:54, Krzysztof Kozlowski wrote:
> On 07/04/2024 19:48, Alex G. wrote:
>> On 3/8/24 03:17, Md Sadre Alam wrote:
>>> Add qpic spi nand driver support. The spi nand
>>> driver currently supported the below commands.
>>>
>>> -- RESET
>>> -- READ ID
>>> -- SET FEATURE
>>> -- GET FEATURE
>>> -- READ PAGE
>>> -- WRITE PAGE
>>> -- ERASE PAGE
>>>
>>> Co-developed-by: Sricharan Ramabadhran <quic_srichara@quicinc.com>
>>> Signed-off-by: Sricharan Ramabadhran <quic_srichara@quicinc.com>
>>> Co-developed-by: Varadarajan Narayanan <quic_varada@quicinc.com>
>>> Signed-off-by: Varadarajan Narayanan <quic_varada@quicinc.com>
>>> Signed-off-by: Md Sadre Alam <quic_mdalam@quicinc.com>
>>> ---
>>
>> For the entire series:
>>
>> Tested-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
>>
>>> diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
>>> index bc7021da2fe9..63764e943d82 100644
>>> --- a/drivers/spi/Kconfig
>>> +++ b/drivers/spi/Kconfig
>>> @@ -882,6 +882,14 @@ config SPI_QCOM_QSPI
>>>    	help
>>>    	  QSPI(Quad SPI) driver for Qualcomm QSPI controller.
>>>    
>>> +config SPI_QPIC_SNAND
>>> +	tristate "QPIC SNAND controller"
>>> +	depends on ARCH_QCOM || COMPILE_TEST
>>
>> Here, it needs to 'select QPIC_COMMON`. Otherwise it can run into
>> unresolved symbols:
>>
>> : drivers/spi/spi-qpic-snand.o: in function `snandc_set_reg':
>>    drivers/spi/spi-qpic-snand.c:56:(.text+0x484): undefined reference to
>> `qcom_offset_to_nandc_reg'
> 
> No, do not select user-visible symbols. If you observe such issues then
> either stubs are missing or depends on.

I apologize for making a bad suggestion. Thank you for pointing it out.

Alex