[PATCH v4 12/16] spi: cadence-quadspi: enable PHY for indirect writes

[Santhosh Kumar K <s-k6@ti.com>]

Enable PHY for indirect writes of at least CQSPI_PHY_MIN_INDIRECT_WRITE_LEN
bytes. PHY is activated only when tuning completed successfully and the
write op runs at the calibrated post-config frequency, matching the same
frequency guard used by the read path.

Thread max_speed_hz from cqspi_mem_process() through cqspi_write() into
cqspi_indirect_write_execute() for the frequency check.

Signed-off-by: Santhosh Kumar K <s-k6@ti.com>
---
 drivers/spi/spi-cadence-quadspi.c | 32 +++++++++++++++++++++++++++----
 1 file changed, 28 insertions(+), 4 deletions(-)

diff --git a/drivers/spi/spi-cadence-quadspi.c b/drivers/spi/spi-cadence-quadspi.c
index 16e3b843f0aa..df7fcdf404a6 100644
--- a/drivers/spi/spi-cadence-quadspi.c
+++ b/drivers/spi/spi-cadence-quadspi.c
@@ -151,6 +151,8 @@ struct cqspi_driver_platdata {
 #define CQSPI_DLL_TIMEOUT_US			300
 /* Minimum transfer length to use DMA for direct reads */
 #define CQSPI_PHY_MIN_DIRECT_READ_LEN		17
+/* Minimum indirect write length to amortize PHY enable/disable overhead */
+#define CQSPI_PHY_MIN_INDIRECT_WRITE_LEN	SZ_1K
 
 /* Runtime_pm autosuspend delay */
 #define CQSPI_AUTOSUSPEND_TIMEOUT		2000
@@ -1240,13 +1242,15 @@ static int cqspi_write_setup(struct cqspi_flash_pdata *f_pdata,
 
 static int cqspi_indirect_write_execute(struct cqspi_flash_pdata *f_pdata,
 					loff_t to_addr, const u8 *txbuf,
-					const size_t n_tx)
+					const size_t n_tx,
+					u32 post_config_max_speed_hz)
 {
 	struct cqspi_st *cqspi = f_pdata->cqspi;
 	struct device *dev = &cqspi->pdev->dev;
 	void __iomem *reg_base = cqspi->iobase;
 	unsigned int remaining = n_tx;
 	unsigned int write_bytes;
+	bool use_tuned_phy_write;
 	int ret;
 
 	if (!refcount_read(&cqspi->refcount))
@@ -1282,6 +1286,18 @@ static int cqspi_indirect_write_execute(struct cqspi_flash_pdata *f_pdata,
 	if (cqspi->apb_ahb_hazard)
 		readl(reg_base + CQSPI_REG_INDIRECTWR);
 
+	/* Use PHY only for large writes at the calibrated rate */
+	use_tuned_phy_write = n_tx >= CQSPI_PHY_MIN_INDIRECT_WRITE_LEN &&
+			      f_pdata->use_tuned_phy &&
+			      f_pdata->phy_write_op.max_freq ==
+				      post_config_max_speed_hz;
+
+	if (use_tuned_phy_write) {
+		ret = cqspi_tune_phy(f_pdata, true);
+		if (ret)
+			goto failwr;
+	}
+
 	while (remaining > 0) {
 		size_t write_words, mod_bytes;
 
@@ -1330,9 +1346,15 @@ static int cqspi_indirect_write_execute(struct cqspi_flash_pdata *f_pdata,
 
 	cqspi_wait_idle(cqspi);
 
+	if (use_tuned_phy_write)
+		cqspi_tune_phy(f_pdata, false);
+
 	return 0;
 
 failwr:
+	if (use_tuned_phy_write)
+		cqspi_tune_phy(f_pdata, false);
+
 	/* Disable interrupt. */
 	writel(0, reg_base + CQSPI_REG_IRQMASK);
 
@@ -1467,7 +1489,8 @@ static void cqspi_configure(struct cqspi_flash_pdata *f_pdata,
 }
 
 static ssize_t cqspi_write(struct cqspi_flash_pdata *f_pdata,
-			   const struct spi_mem_op *op)
+			   const struct spi_mem_op *op,
+			   u32 post_config_max_speed_hz)
 {
 	struct cqspi_st *cqspi = f_pdata->cqspi;
 	loff_t to = op->addr.val;
@@ -1494,7 +1517,8 @@ static ssize_t cqspi_write(struct cqspi_flash_pdata *f_pdata,
 		return cqspi_wait_idle(cqspi);
 	}
 
-	return cqspi_indirect_write_execute(f_pdata, to, buf, len);
+	return cqspi_indirect_write_execute(f_pdata, to, buf, len,
+					    post_config_max_speed_hz);
 }
 
 static bool cqspi_use_tuned_phy(struct cqspi_flash_pdata *f_pdata,
@@ -1710,7 +1734,7 @@ static int cqspi_mem_process(struct spi_mem *mem, const struct spi_mem_op *op)
 	if (!op->addr.nbytes || !op->data.buf.out)
 		return cqspi_command_write(f_pdata, op);
 
-	return cqspi_write(f_pdata, op);
+	return cqspi_write(f_pdata, op, mem->spi->post_config_max_speed_hz);
 }
 
 static int cqspi_exec_mem_op(struct spi_mem *mem, const struct spi_mem_op *op)
-- 
2.34.1