[PATCH v2 08/11] spi: cadence-qspi: add early busywait to cqspi_wait_for_bit()

Théo Lebrun
2024-04-05T15:02:21Z

If the CQSPI_BUSYWAIT_EARLY quirk flag is on, 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.

Behavior is hidden behind a quirk flag to keep the previous behavior the
same on all platforms.

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

Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
---
drivers/spi/spi-cadence-quadspi.c | 34 +++++++++++++++++++++++++---------
1 file changed, 25 insertions(+), 9 deletions(-)

diff --git a/drivers/spi/spi-cadence-quadspi.c b/drivers/spi/spi-cadence-quadspi.c
index ebb8c35f50fd..230aad490e03 100644
--- a/drivers/spi/spi-cadence-quadspi.c
+++ b/drivers/spi/spi-cadence-quadspi.c
@@ -44,6 +44,7 @@ static_assert(CQSPI_MAX_CHIPSELECT <= SPI_CS_CNT_MAX);
#define CQSPI_NEEDS_APB_AHB_HAZARD_WAR BIT(5)
#define CQSPI_DETECT_FIFO_DEPTH BIT(6)
#define CQSPI_RD_NO_IRQ BIT(7)
+#define CQSPI_BUSYWAIT_EARLY BIT(8)

/* Capabilities */
#define CQSPI_SUPPORTS_OCTAL BIT(0)
@@ -110,7 +111,7 @@ struct cqspi_st {

struct cqspi_driver_platdata {
u32 hwcaps_mask;
- u8 quirks;
+ u16 quirks;
int (*indirect_read_dma)(struct cqspi_flash_pdata *f_pdata,
u_char *rxbuf, loff_t from_addr, size_t n_rx);
u32 (*get_dma_status)(struct cqspi_st *cqspi);
@@ -121,6 +122,7 @@ 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
@@ -299,13 +301,27 @@ 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 && ddata && ddata->quirks & CQSPI_BUSYWAIT_EARLY) {
+ 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)
@@ -435,8 +451,8 @@ 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");
@@ -791,8 +807,8 @@ 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;
@@ -1092,8 +1108,8 @@ 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