Merge tag 'spi-fix-v6.7-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi

Pull spi fixes from Mark Brown:
 "A few bigger things here, the main one being that there were changes
  to the atmel driver in this cycle which made it possible to kill
  transfers being used for filesystem I/O which turned out to be very
  disruptive, the series of patches here undoes that and hardens things
  up further.

  There's also a few smaller driver specific changes, the main one being
  to revert a change that duplicted delays"

* tag 'spi-fix-v6.7-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi:
  spi: atmel: Fix clock issue when using devices with different polarities
  spi: spi-imx: correctly configure burst length when using dma
  spi: cadence: revert "Add SPI transfer delays"
  spi: atmel: Prevent spi transfers from being killed
  spi: atmel: Drop unused defines
  spi: atmel: Do not cancel a transfer upon any signal

3 files changed, 96 insertions, 15 deletions

diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c
index 6aa8adbe4170cd..bad34998454a80 100644
--- a/drivers/spi/spi-atmel.c
+++ b/drivers/spi/spi-atmel.c
@@ -22,6 +22,7 @@
 #include <linux/gpio/consumer.h>
 #include <linux/pinctrl/consumer.h>
 #include <linux/pm_runtime.h>
+#include <linux/iopoll.h>
 #include <trace/events/spi.h>
 
 /* SPI register offsets */
@@ -233,9 +234,6 @@
  */
 #define DMA_MIN_BYTES	16
 
-#define SPI_DMA_MIN_TIMEOUT	(msecs_to_jiffies(1000))
-#define SPI_DMA_TIMEOUT_PER_10K	(msecs_to_jiffies(4))
-
 #define AUTOSUSPEND_TIMEOUT	2000
 
 struct atmel_spi_caps {
@@ -279,6 +277,7 @@ struct atmel_spi {
 	bool			keep_cs;
 
 	u32			fifo_size;
+	bool			last_polarity;
 	u8			native_cs_free;
 	u8			native_cs_for_gpio;
 };
@@ -292,6 +291,22 @@ struct atmel_spi_device {
 #define INVALID_DMA_ADDRESS	0xffffffff
 
 /*
+ * This frequency can be anything supported by the controller, but to avoid
+ * unnecessary delay, the highest possible frequency is chosen.
+ *
+ * This frequency is the highest possible which is not interfering with other
+ * chip select registers (see Note for Serial Clock Bit Rate configuration in
+ * Atmel-11121F-ATARM-SAMA5D3-Series-Datasheet_02-Feb-16, page 1283)
+ */
+#define DUMMY_MSG_FREQUENCY	0x02
+/*
+ * 8 bits is the minimum data the controller is capable of sending.
+ *
+ * This message can be anything as it should not be treated by any SPI device.
+ */
+#define DUMMY_MSG		0xAA
+
+/*
  * Version 2 of the SPI controller has
  *  - CR.LASTXFER
  *  - SPI_MR.DIV32 may become FDIV or must-be-zero (here: always zero)
@@ -305,6 +320,43 @@ static bool atmel_spi_is_v2(struct atmel_spi *as)
 }
 
 /*
+ * Send a dummy message.
+ *
+ * This is sometimes needed when using a CS GPIO to force clock transition when
+ * switching between devices with different polarities.
+ */
+static void atmel_spi_send_dummy(struct atmel_spi *as, struct spi_device *spi, int chip_select)
+{
+	u32 status;
+	u32 csr;
+
+	/*
+	 * Set a clock frequency to allow sending message on SPI bus.
+	 * The frequency here can be anything, but is needed for
+	 * the controller to send the data.
+	 */
+	csr = spi_readl(as, CSR0 + 4 * chip_select);
+	csr = SPI_BFINS(SCBR, DUMMY_MSG_FREQUENCY, csr);
+	spi_writel(as, CSR0 + 4 * chip_select, csr);
+
+	/*
+	 * Read all data coming from SPI bus, needed to be able to send
+	 * the message.
+	 */
+	spi_readl(as, RDR);
+	while (spi_readl(as, SR) & SPI_BIT(RDRF)) {
+		spi_readl(as, RDR);
+		cpu_relax();
+	}
+
+	spi_writel(as, TDR, DUMMY_MSG);
+
+	readl_poll_timeout_atomic(as->regs + SPI_SR, status,
+				  (status & SPI_BIT(TXEMPTY)), 1, 1000);
+}
+
+
+/*
  * Earlier SPI controllers (e.g. on at91rm9200) have a design bug whereby
  * they assume that spi slave device state will not change on deselect, so
  * that automagic deselection is OK.  ("NPCSx rises if no data is to be
@@ -320,11 +372,17 @@ static bool atmel_spi_is_v2(struct atmel_spi *as)
  * Master on Chip Select 0.")  No workaround exists for that ... so for
  * nCS0 on that chip, we (a) don't use the GPIO, (b) can't support CS_HIGH,
  * and (c) will trigger that first erratum in some cases.
+ *
+ * When changing the clock polarity, the SPI controller waits for the next
+ * transmission to enforce the default clock state. This may be an issue when
+ * using a GPIO as Chip Select: the clock level is applied only when the first
+ * packet is sent, once the CS has already been asserted. The workaround is to
+ * avoid this by sending a first (dummy) message before toggling the CS state.
  */
-
 static void cs_activate(struct atmel_spi *as, struct spi_device *spi)
 {
 	struct atmel_spi_device *asd = spi->controller_state;
+	bool new_polarity;
 	int chip_select;
 	u32 mr;
 
@@ -353,6 +411,25 @@ static void cs_activate(struct atmel_spi *as, struct spi_device *spi)
 		}
 
 		mr = spi_readl(as, MR);
+
+		/*
+		 * Ensures the clock polarity is valid before we actually
+		 * assert the CS to avoid spurious clock edges to be
+		 * processed by the spi devices.
+		 */
+		if (spi_get_csgpiod(spi, 0)) {
+			new_polarity = (asd->csr & SPI_BIT(CPOL)) != 0;
+			if (new_polarity != as->last_polarity) {
+				/*
+				 * Need to disable the GPIO before sending the dummy
+				 * message because it is already set by the spi core.
+				 */
+				gpiod_set_value_cansleep(spi_get_csgpiod(spi, 0), 0);
+				atmel_spi_send_dummy(as, spi, chip_select);
+				as->last_polarity = new_polarity;
+				gpiod_set_value_cansleep(spi_get_csgpiod(spi, 0), 1);
+			}
+		}
 	} else {
 		u32 cpol = (spi->mode & SPI_CPOL) ? SPI_BIT(CPOL) : 0;
 		int i;
@@ -1336,12 +1413,10 @@ static int atmel_spi_one_transfer(struct spi_controller *host,
 		}
 
 		dma_timeout = msecs_to_jiffies(spi_controller_xfer_timeout(host, xfer));
-		ret_timeout = wait_for_completion_interruptible_timeout(&as->xfer_completion,
-									dma_timeout);
-		if (ret_timeout <= 0) {
-			dev_err(&spi->dev, "spi transfer %s\n",
-				!ret_timeout ? "timeout" : "canceled");
-			as->done_status = ret_timeout < 0 ? ret_timeout : -EIO;
+		ret_timeout = wait_for_completion_timeout(&as->xfer_completion, dma_timeout);
+		if (!ret_timeout) {
+			dev_err(&spi->dev, "spi transfer timeout\n");
+			as->done_status = -EIO;
 		}
 
 		if (as->done_status)
diff --git a/drivers/spi/spi-cadence.c b/drivers/spi/spi-cadence.c
index 1f2f8c717df61f..a50eb4db79de8e 100644
--- a/drivers/spi/spi-cadence.c
+++ b/drivers/spi/spi-cadence.c
@@ -451,7 +451,6 @@ static int cdns_transfer_one(struct spi_controller *ctlr,
 		udelay(10);
 
 	cdns_spi_process_fifo(xspi, xspi->tx_fifo_depth, 0);
-	spi_transfer_delay_exec(transfer);
 
 	cdns_spi_write(xspi, CDNS_SPI_IER, CDNS_SPI_IXR_DEFAULT);
 	return transfer->len;
diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
index 498e35c8db2c1d..272bc871a848b8 100644
--- a/drivers/spi/spi-imx.c
+++ b/drivers/spi/spi-imx.c
@@ -659,11 +659,18 @@ static int mx51_ecspi_prepare_transfer(struct spi_imx_data *spi_imx,
 		ctrl |= (spi_imx->target_burst * 8 - 1)
 			<< MX51_ECSPI_CTRL_BL_OFFSET;
 	else {
-		if (spi_imx->count >= 512)
-			ctrl |= 0xFFF << MX51_ECSPI_CTRL_BL_OFFSET;
-		else
-			ctrl |= (spi_imx->count * spi_imx->bits_per_word - 1)
+		if (spi_imx->usedma) {
+			ctrl |= (spi_imx->bits_per_word *
+				spi_imx_bytes_per_word(spi_imx->bits_per_word) - 1)
 				<< MX51_ECSPI_CTRL_BL_OFFSET;
+		} else {
+			if (spi_imx->count >= MX51_ECSPI_CTRL_MAX_BURST)
+				ctrl |= (MX51_ECSPI_CTRL_MAX_BURST - 1)
+						<< MX51_ECSPI_CTRL_BL_OFFSET;
+			else
+				ctrl |= (spi_imx->count * spi_imx->bits_per_word - 1)
+						<< MX51_ECSPI_CTRL_BL_OFFSET;
+		}
 	}
 
 	/* set clock speed */