[1/4] spi: lantiq: Synchronize interrupt handlers and transfers

diff --git a/drivers/spi/spi-lantiq-ssc.c b/drivers/spi/spi-lantiq-ssc.c
index 1fd7ee53d451..b67f5925bcb0 100644
--- a/drivers/spi/spi-lantiq-ssc.c
+++ b/drivers/spi/spi-lantiq-ssc.c
@@ -6,6 +6,7 @@ 
 
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/mutex.h>
 #include <linux/of_device.h>
 #include <linux/clk.h>
 #include <linux/io.h>
@@ -13,7 +14,6 @@ 
 #include <linux/interrupt.h>
 #include <linux/sched.h>
 #include <linux/completion.h>
-#include <linux/spinlock.h>
 #include <linux/err.h>
 #include <linux/gpio.h>
 #include <linux/pm_runtime.h>
@@ -50,8 +50,8 @@ 
 #define LTQ_SPI_RXCNT		0x84
 #define LTQ_SPI_DMACON		0xec
 #define LTQ_SPI_IRNEN		0xf4
-#define LTQ_SPI_IRNICR		0xf8
-#define LTQ_SPI_IRNCR		0xfc
+#define LTQ_SPI_IRNCR		0xf8
+#define LTQ_SPI_IRNICR		0xfc
 
 #define LTQ_SPI_CLC_SMC_S	16	/* Clock divider for sleep mode */
 #define LTQ_SPI_CLC_SMC_M	(0xFF << LTQ_SPI_CLC_SMC_S)
@@ -171,9 +171,7 @@  struct lantiq_ssc_spi {
 	struct clk			*fpi_clk;
 	const struct lantiq_ssc_hwcfg	*hwcfg;
 
-	spinlock_t			lock;
-	struct workqueue_struct		*wq;
-	struct work_struct		work;
+	struct mutex			lock;
 
 	const u8			*tx;
 	u8				*rx;
@@ -186,6 +184,8 @@  struct lantiq_ssc_spi {
 	unsigned int			base_cs;
 };
 
+static void lantiq_ssc_busy_wait(struct lantiq_ssc_spi *spi);
+
 static u32 lantiq_ssc_readl(const struct lantiq_ssc_spi *spi, u32 reg)
 {
 	return __raw_readl(spi->regbase + reg);
@@ -464,8 +464,6 @@  static int lantiq_ssc_unprepare_message(struct spi_master *master,
 {
 	struct lantiq_ssc_spi *spi = spi_master_get_devdata(master);
 
-	flush_workqueue(spi->wq);
-
 	/* Disable transmitter and receiver while idle */
 	lantiq_ssc_maskl(spi, 0, LTQ_SPI_CON_TXOFF | LTQ_SPI_CON_RXOFF,
 			 LTQ_SPI_CON);
@@ -610,10 +608,8 @@  static void rx_request(struct lantiq_ssc_spi *spi)
 	lantiq_ssc_writel(spi, rxreq, LTQ_SPI_RXREQ);
 }
 
-static irqreturn_t lantiq_ssc_xmit_interrupt(int irq, void *data)
+static irqreturn_t lantiq_ssc_xmit_interrupt(struct lantiq_ssc_spi *spi)
 {
-	struct lantiq_ssc_spi *spi = data;
-
 	if (spi->tx) {
 		if (spi->rx && spi->rx_todo)
 			rx_fifo_read_full_duplex(spi);
@@ -638,19 +634,15 @@  static irqreturn_t lantiq_ssc_xmit_interrupt(int irq, void *data)
 	return IRQ_HANDLED;
 
 completed:
-	queue_work(spi->wq, &spi->work);
+	lantiq_ssc_busy_wait(spi);
 
 	return IRQ_HANDLED;
 }
 
-static irqreturn_t lantiq_ssc_err_interrupt(int irq, void *data)
+static irqreturn_t lantiq_ssc_err_interrupt(struct lantiq_ssc_spi *spi)
 {
-	struct lantiq_ssc_spi *spi = data;
 	u32 stat = lantiq_ssc_readl(spi, LTQ_SPI_STAT);
 
-	if (!(stat & LTQ_SPI_STAT_ERRORS))
-		return IRQ_NONE;
-
 	if (stat & LTQ_SPI_STAT_RUE)
 		dev_err(spi->dev, "receive underflow error\n");
 	if (stat & LTQ_SPI_STAT_TUE)
@@ -670,17 +662,39 @@  static irqreturn_t lantiq_ssc_err_interrupt(int irq, void *data)
 	/* set bad status so it can be retried */
 	if (spi->master->cur_msg)
 		spi->master->cur_msg->status = -EIO;
-	queue_work(spi->wq, &spi->work);
+
+	spi_finalize_current_transfer(spi->master);
 
 	return IRQ_HANDLED;
 }
 
+static irqreturn_t lantiq_ssc_isr(int irq, void *data)
+{
+	struct lantiq_ssc_spi *spi = data;
+	const struct lantiq_ssc_hwcfg *hwcfg = spi->hwcfg;
+	irqreturn_t ret = IRQ_NONE;
+	u32 val;
+
+	mutex_lock(&spi->lock);
+	val = lantiq_ssc_readl(spi, LTQ_SPI_IRNCR);
+	lantiq_ssc_maskl(spi, val, 0, LTQ_SPI_IRNEN);
+
+	if (val & LTQ_SPI_IRNEN_E)
+		ret = lantiq_ssc_err_interrupt(spi);
+
+	if ((val & hwcfg->irnen_t) || (val & hwcfg->irnen_r))
+		ret = lantiq_ssc_xmit_interrupt(spi);
+
+	lantiq_ssc_maskl(spi, 0, val, LTQ_SPI_IRNEN);
+	mutex_unlock(&spi->lock);
+
+	return ret;
+}
+
 static int transfer_start(struct lantiq_ssc_spi *spi, struct spi_device *spidev,
 			  struct spi_transfer *t)
 {
-	unsigned long flags;
-
-	spin_lock_irqsave(&spi->lock, flags);
+	mutex_lock(&spi->lock);
 
 	spi->tx = t->tx_buf;
 	spi->rx = t->rx_buf;
@@ -700,7 +714,7 @@  static int transfer_start(struct lantiq_ssc_spi *spi, struct spi_device *spidev,
 			rx_request(spi);
 	}
 
-	spin_unlock_irqrestore(&spi->lock, flags);
+	mutex_unlock(&spi->lock);
 
 	return t->len;
 }
@@ -712,14 +726,11 @@  static int transfer_start(struct lantiq_ssc_spi *spi, struct spi_device *spidev,
  * write the last word to the wire, not when it is finished. Do busy
  * waiting till it finishes.
  */
-static void lantiq_ssc_bussy_work(struct work_struct *work)
+static void lantiq_ssc_busy_wait(struct lantiq_ssc_spi *spi)
 {
-	struct lantiq_ssc_spi *spi;
 	unsigned long long timeout = 8LL * 1000LL;
 	unsigned long end;
 
-	spi = container_of(work, typeof(*spi), work);
-
 	do_div(timeout, spi->speed_hz);
 	timeout += timeout + 100; /* some tolerance */
 
@@ -838,18 +849,18 @@  static int lantiq_ssc_probe(struct platform_device *pdev)
 		goto err_master_put;
 	}
 
-	err = devm_request_irq(dev, rx_irq, lantiq_ssc_xmit_interrupt,
-			       0, LTQ_SPI_RX_IRQ_NAME, spi);
+	err = devm_request_threaded_irq(dev, rx_irq, NULL, lantiq_ssc_isr,
+					IRQF_ONESHOT, LTQ_SPI_RX_IRQ_NAME, spi);
 	if (err)
 		goto err_master_put;
 
-	err = devm_request_irq(dev, tx_irq, lantiq_ssc_xmit_interrupt,
-			       0, LTQ_SPI_TX_IRQ_NAME, spi);
+	err = devm_request_threaded_irq(dev, tx_irq, NULL, lantiq_ssc_isr,
+					IRQF_ONESHOT, LTQ_SPI_TX_IRQ_NAME, spi);
 	if (err)
 		goto err_master_put;
 
-	err = devm_request_irq(dev, err_irq, lantiq_ssc_err_interrupt,
-			       0, LTQ_SPI_ERR_IRQ_NAME, spi);
+	err = devm_request_threaded_irq(dev, err_irq, NULL, lantiq_ssc_isr,
+					IRQF_ONESHOT, LTQ_SPI_ERR_IRQ_NAME, spi);
 	if (err)
 		goto err_master_put;
 
@@ -882,7 +893,7 @@  static int lantiq_ssc_probe(struct platform_device *pdev)
 	spi->base_cs = 1;
 	of_property_read_u32(pdev->dev.of_node, "base-cs", &spi->base_cs);
 
-	spin_lock_init(&spi->lock);
+	mutex_init(&spi->lock);
 	spi->bits_per_word = 8;
 	spi->speed_hz = 0;
 
@@ -899,13 +910,6 @@  static int lantiq_ssc_probe(struct platform_device *pdev)
 	master->bits_per_word_mask = SPI_BPW_RANGE_MASK(2, 8) |
 				     SPI_BPW_MASK(16) | SPI_BPW_MASK(32);
 
-	spi->wq = alloc_ordered_workqueue(dev_name(dev), 0);
-	if (!spi->wq) {
-		err = -ENOMEM;
-		goto err_clk_put;
-	}
-	INIT_WORK(&spi->work, lantiq_ssc_bussy_work);
-
 	id = lantiq_ssc_readl(spi, LTQ_SPI_ID);
 	spi->tx_fifo_size = (id & LTQ_SPI_ID_TXFS_M) >> LTQ_SPI_ID_TXFS_S;
 	spi->rx_fifo_size = (id & LTQ_SPI_ID_RXFS_M) >> LTQ_SPI_ID_RXFS_S;
@@ -921,13 +925,11 @@  static int lantiq_ssc_probe(struct platform_device *pdev)
 	err = devm_spi_register_master(dev, master);
 	if (err) {
 		dev_err(dev, "failed to register spi_master\n");
-		goto err_wq_destroy;
+		goto err_clk_put;
 	}
 
 	return 0;
 
-err_wq_destroy:
-	destroy_workqueue(spi->wq);
 err_clk_put:
 	clk_put(spi->fpi_clk);
 err_clk_disable:
@@ -948,7 +950,6 @@  static int lantiq_ssc_remove(struct platform_device *pdev)
 	tx_fifo_flush(spi);
 	hw_enter_config_mode(spi);
 
-	destroy_workqueue(spi->wq);
 	clk_disable_unprepare(spi->spi_clk);
 	clk_put(spi->fpi_clk);