[v2,0/9] BCMA support for brcmnand

Hi all,

This patch series adds support for the BRCMNAND controller revision 3.4
embedded in MIPS-based SoCs such as 5357, typically found in the Netgear
WNR3500L v2 and other kinds of Wi-Fi routers. The upstream platform that
uses this controller is under arch/mips/bcm47xx/ and does not use Device
Tree (and probably never will by now). BCMA (Broadcom AMBA) is a special
kind of discoverable memory mapped interface which requires the use of
special accessors to read from/write to the hardware block.

The integration of brcmnand into that SoC is a bit quirky in that every
register offering byte level data about the flash (OOB, device ID, etc.)
requires byte swapping. The command shift should also have been 24, but
is in fact 0, took me a while to understand why no reads were actually
working because of that.

This has been tested with Linux 5.10.82 and Linus' master with OpenWrt
and confirmed that the squashfs + jffs2 overlay that OpenWrt creates is
entirely functional and that written data is made persistent.

Changes in v2:

- re-ordered the patch such that the soc variable is initialized as
  early as possible
- corrected bug in the conversion of brcmnand_init_cs() which
  incorrectly used the wrong device_node variable (parent instead of
  child)
- took Andy's feedback to make the test for a valid interrupt to be > 0
  while calling platform_get_irq_optional()
- utilized static branch (disabled by default) and conditional
  compilation and confirm with disassembly that the generated code is
  as efficient as before if not enabling the BCMA shim and as efficient
  as possible if enabling BCMA shim
- updated BCMA shim driver descriptor, author and added helper function
  to encapsulate the container_of usage
- added comment to explain why a slightly different platform device name
  is used for the 5357-style NAND controller

Florian Fainelli (9):
  mtd: rawnand: brcmnand: Assign soc as early as possible
  mtd: rawnand: brcmnand: Allow SoC to provide I/O operations
  mtd: rawnand: brcmnand: Avoid pdev in brcmnand_init_cs()
  mtd: rawnand: brcmnand: Move OF operations out of brcmnand_init_cs()
  mtd: rawnand: brcmnand: Allow working without interrupts
  mtd: rawnand: brcmnand: Add platform data structure for BCMA
  mtd: rawnand: brcmnand: Allow platform data instantation
  mtd: rawnand: brcmnand: BCMA controller uses command shift of 0
  mtd: rawnand: brcmnand: Add BCMA shim

 MAINTAINERS                                 |   1 +
 drivers/bcma/driver_chipcommon_nflash.c     |  20 ++-
 drivers/mtd/nand/raw/Kconfig                |  13 ++
 drivers/mtd/nand/raw/brcmnand/Makefile      |   2 +
 drivers/mtd/nand/raw/brcmnand/bcma_nand.c   | 132 ++++++++++++++++
 drivers/mtd/nand/raw/brcmnand/brcmnand.c    | 160 +++++++++++++-------
 drivers/mtd/nand/raw/brcmnand/brcmnand.h    |  29 ++++
 include/linux/bcma/bcma_driver_chipcommon.h |   5 +
 include/linux/platform_data/brcmnand.h      |  12 ++
 9 files changed, 321 insertions(+), 53 deletions(-)
 create mode 100644 drivers/mtd/nand/raw/brcmnand/bcma_nand.c
 create mode 100644 include/linux/platform_data/brcmnand.h

On 1/6/2022 4:13 PM, Florian Fainelli wrote:
> Allow a brcmnand_soc instance to provide a custom set of I/O operations
> which we will require when using this driver on a BCMA bus which is not
> directly memory mapped I/O. Update the nand_{read,write}_reg accordingly
> to use the SoC operations if provided.
> 
> To minimize the penalty on other SoCs which do support standard MMIO
> accesses, we use a static key which is disabled by default and gets
> enabled if a soc implementation does provide I/O operations.
> 
> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
> ---

[snip]

>   	init_completion(&ctrl->done);
>   	init_completion(&ctrl->dma_done);
>   	init_completion(&ctrl->edu_done);
> @@ -3145,6 +3169,8 @@ int brcmnand_probe(struct platform_device *pdev, struct brcmnand_soc *soc)
>   		/* Enable interrupt */
>   		ctrl->soc->ctlrdy_ack(ctrl->soc);
>   		ctrl->soc->ctlrdy_set_enabled(ctrl->soc, true);
> +		if (brcmnand_soc_has_ops(soc))
> +			static_branch_enable(&brcmnand_soc_has_ops_key);

This hunk got mistakenly added with a rebase, I will wait for additional 
comments before spinning a new version.