2024-04-10 09:30:35

by Théo Lebrun

[permalink] [raw]
Subject: [PATCH v3 6/9] spi: cadence-qspi: add early busywait to cqspi_wait_for_bit()

Call readl_relaxed_poll_timeout() with no sleep at the start of
cqspi_wait_for_bit(). If its short timeout expires, a sleeping
readl_relaxed_poll_timeout() call takes the relay.

The reason is to avoid hrtimer interrupts on the system. All read
operations are expected to take less than 100µs.

Signed-off-by: Théo Lebrun <[email protected]>
---
drivers/spi/spi-cadence-quadspi.c | 31 +++++++++++++++++++++++--------
1 file changed, 23 insertions(+), 8 deletions(-)

diff --git a/drivers/spi/spi-cadence-quadspi.c b/drivers/spi/spi-cadence-quadspi.c
index cde84d10678e..fecb76cfb932 100644
--- a/drivers/spi/spi-cadence-quadspi.c
+++ b/drivers/spi/spi-cadence-quadspi.c
@@ -120,6 +120,7 @@ struct cqspi_driver_platdata {
/* Operation timeout value */
#define CQSPI_TIMEOUT_MS 500
#define CQSPI_READ_TIMEOUT_MS 10
+#define CQSPI_BUSYWAIT_TIMEOUT_US 500

/* Runtime_pm autosuspend delay */
#define CQSPI_AUTOSUSPEND_TIMEOUT 2000
@@ -298,13 +299,27 @@ struct cqspi_driver_platdata {

#define CQSPI_REG_VERSAL_DMA_VAL 0x602

-static int cqspi_wait_for_bit(void __iomem *reg, const u32 mask, bool clr)
+static int cqspi_wait_for_bit(const struct cqspi_driver_platdata *ddata,
+ void __iomem *reg, const u32 mask, bool clr,
+ bool busywait)
{
+ u64 timeout_us = CQSPI_TIMEOUT_MS * USEC_PER_MSEC;
u32 val;

+ if (busywait) {
+ int ret = readl_relaxed_poll_timeout(reg, val,
+ (((clr ? ~val : val) & mask) == mask),
+ 0, CQSPI_BUSYWAIT_TIMEOUT_US);
+
+ if (ret != -ETIMEDOUT)
+ return ret;
+
+ timeout_us -= CQSPI_BUSYWAIT_TIMEOUT_US;
+ }
+
return readl_relaxed_poll_timeout(reg, val,
(((clr ? ~val : val) & mask) == mask),
- 10, CQSPI_TIMEOUT_MS * 1000);
+ 10, timeout_us);
}

static bool cqspi_is_idle(struct cqspi_st *cqspi)
@@ -434,8 +449,8 @@ static int cqspi_exec_flash_cmd(struct cqspi_st *cqspi, unsigned int reg)
writel(reg, reg_base + CQSPI_REG_CMDCTRL);

/* Polling for completion. */
- ret = cqspi_wait_for_bit(reg_base + CQSPI_REG_CMDCTRL,
- CQSPI_REG_CMDCTRL_INPROGRESS_MASK, 1);
+ ret = cqspi_wait_for_bit(cqspi->ddata, reg_base + CQSPI_REG_CMDCTRL,
+ CQSPI_REG_CMDCTRL_INPROGRESS_MASK, 1, true);
if (ret) {
dev_err(&cqspi->pdev->dev,
"Flash command execution timed out.\n");
@@ -790,8 +805,8 @@ static int cqspi_indirect_read_execute(struct cqspi_flash_pdata *f_pdata,
}

/* Check indirect done status */
- ret = cqspi_wait_for_bit(reg_base + CQSPI_REG_INDIRECTRD,
- CQSPI_REG_INDIRECTRD_DONE_MASK, 0);
+ ret = cqspi_wait_for_bit(cqspi->ddata, reg_base + CQSPI_REG_INDIRECTRD,
+ CQSPI_REG_INDIRECTRD_DONE_MASK, 0, true);
if (ret) {
dev_err(dev, "Indirect read completion error (%i)\n", ret);
goto failrd;
@@ -1091,8 +1106,8 @@ static int cqspi_indirect_write_execute(struct cqspi_flash_pdata *f_pdata,
}

/* Check indirect done status */
- ret = cqspi_wait_for_bit(reg_base + CQSPI_REG_INDIRECTWR,
- CQSPI_REG_INDIRECTWR_DONE_MASK, 0);
+ ret = cqspi_wait_for_bit(cqspi->ddata, reg_base + CQSPI_REG_INDIRECTWR,
+ CQSPI_REG_INDIRECTWR_DONE_MASK, 0, false);
if (ret) {
dev_err(dev, "Indirect write completion error (%i)\n", ret);
goto failwr;

--
2.44.0