[PATCH 5/5] spi: cadence-xspi: Add support for panic writes

[Paul Cercueil <paul.cercueil@bootlin.com>]

From: Tanmay Jagdale <tanmay@marvell.com>

Advertise support for panic writes. When a memory op is received with
the 'panic' flag set, the driver will then work without relying on
interrupts and without sleeping.

Signed-off-by: Tanmay Jagdale <tanmay@marvell.com>
Co-developed-by: Paul Cercueil <paul.cercueil@bootlin.com>
Signed-off-by: Paul Cercueil <paul.cercueil@bootlin.com>
---
 drivers/spi/spi-cadence-xspi.c | 26 ++++++++++++++++++--------
 1 file changed, 18 insertions(+), 8 deletions(-)

diff --git a/drivers/spi/spi-cadence-xspi.c b/drivers/spi/spi-cadence-xspi.c
index 09ed2afbd4af..0b7162740940 100644
--- a/drivers/spi/spi-cadence-xspi.c
+++ b/drivers/spi/spi-cadence-xspi.c
@@ -350,10 +350,11 @@ struct cdns_xspi_dev {
 	void (*set_interrupts_handler)(struct cdns_xspi_dev *cdns_xspi, bool enabled);
 
 	bool xfer_in_progress;
+	bool panic_write;
 	int current_xfer_qword;
 };
 
-static int cdns_xspi_wait_for_controller_idle(struct cdns_xspi_dev *cdns_xspi)
+static int cdns_xspi_wait_for_controller_idle(struct cdns_xspi_dev *cdns_xspi, bool sleep)
 {
 	u32 ctrl_stat;
 
@@ -362,7 +363,7 @@ static int cdns_xspi_wait_for_controller_idle(struct cdns_xspi_dev *cdns_xspi)
 					  ctrl_stat,
 					  ((ctrl_stat &
 					    CDNS_XSPI_CTRL_BUSY) == 0),
-					  100, 1000);
+					  sleep ? 100 : 0, 1000);
 }
 
 static bool cdns_xspi_is_stig_ready(struct cdns_xspi_dev *cdns_xspi, bool sleep)
@@ -549,7 +550,7 @@ static int cdns_xspi_send_stig_command(struct cdns_xspi_dev *cdns_xspi,
 	int ret;
 	int dummybytes = op->dummy.nbytes;
 
-	ret = cdns_xspi_wait_for_controller_idle(cdns_xspi);
+	ret = cdns_xspi_wait_for_controller_idle(cdns_xspi, !op->panic_write);
 	if (ret < 0)
 		return -EIO;
 
@@ -586,23 +587,23 @@ static int cdns_xspi_send_stig_command(struct cdns_xspi_dev *cdns_xspi,
 
 		cdns_xspi_trigger_command(cdns_xspi, cmd_regs);
 
-		if (cdns_xspi->irq >= 0) {
+		if (cdns_xspi->irq >= 0 && !op->panic_write) {
 			wait_for_completion(&cdns_xspi->sdma_complete);
 			if (cdns_xspi->sdma_error) {
 				cdns_xspi->set_interrupts_handler(cdns_xspi, false);
 				return -EIO;
 			}
-		} else if (!cdns_xspi_is_sdma_ready(cdns_xspi, true)) {
+		} else if (!cdns_xspi_is_sdma_ready(cdns_xspi, !op->panic_write)) {
 			return -EIO;
 		}
 
 		cdns_xspi->sdma_handler(cdns_xspi);
 	}
 
-	if (cdns_xspi->irq >= 0) {
+	if (cdns_xspi->irq >= 0 && !op->panic_write) {
 		wait_for_completion(&cdns_xspi->cmd_complete);
 		cdns_xspi->set_interrupts_handler(cdns_xspi, false);
-	} else if (!cdns_xspi_is_stig_ready(cdns_xspi, true)) {
+	} else if (!cdns_xspi_is_stig_ready(cdns_xspi, !op->panic_write)) {
 		return -EIO;
 	}
 
@@ -622,6 +623,8 @@ static int cdns_xspi_mem_op(struct cdns_xspi_dev *cdns_xspi,
 	if (cdns_xspi->cur_cs != spi_get_chipselect(mem->spi, 0))
 		cdns_xspi->cur_cs = spi_get_chipselect(mem->spi, 0);
 
+	cdns_xspi->panic_write = op->panic_write;
+
 	return cdns_xspi_send_stig_command(cdns_xspi, op,
 					   (dir != SPI_MEM_NO_DATA));
 }
@@ -831,9 +834,11 @@ static bool cdns_xspi_is_dll_locked(struct cdns_xspi_dev *cdns_xspi)
 {
 	u32 dll_lock;
 
+	/* Busy-wait in case we wake up the PHY from suspend to do a panic write */
 	return !readl_relaxed_poll_timeout(cdns_xspi->iobase +
 		CDNS_XSPI_INTR_STATUS_REG,
-		dll_lock, ((dll_lock & CDNS_XSPI_DLL_LOCK) == 1), 10, 10000);
+		dll_lock, ((dll_lock & CDNS_XSPI_DLL_LOCK) == 1),
+		cdns_xspi->panic_write ? 0 : 10, 10000);
 }
 
 /* Static configuration of PHY */
@@ -1186,6 +1191,10 @@ static int cdns_xspi_transfer_one_message_b0(struct spi_controller *controller,
 }
 #endif
 
+static const struct spi_controller_mem_caps cdns_xspi_mem_caps = {
+	.panic_write = true,
+};
+
 static int cdns_xspi_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -1306,6 +1315,7 @@ static int cdns_xspi_probe(struct platform_device *pdev)
 	}
 
 	host->num_chipselect = 1 << cdns_xspi->hw_num_banks;
+	host->mem_caps = &cdns_xspi_mem_caps;
 
 	ret = devm_spi_register_controller(dev, host);
 	if (ret) {
-- 
2.47.3