[PATCH 4/8] spi: fsl-qspi: add a clock disable quirk

[Alex Elder <elder@riscstar.com>]

The SpacemiT K1 SoC QSPI implementation needs to avoid shutting
off the clock when changing its rate.  Add a new quirk to indicate
the clock should not be disabled/enabled when changing its rate
for operations.

Signed-off-by: Alex Elder <elder@riscstar.com>
---
 drivers/spi/spi-fsl-qspi.c | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/drivers/spi/spi-fsl-qspi.c b/drivers/spi/spi-fsl-qspi.c
index 1e27647dd2a09..703a7df394c00 100644
--- a/drivers/spi/spi-fsl-qspi.c
+++ b/drivers/spi/spi-fsl-qspi.c
@@ -197,6 +197,11 @@
  */
 #define QUADSPI_QUIRK_USE_TDH_SETTING	BIT(5)
 
+/*
+ * Do not disable the "qspi" clock when changing its rate.
+ */
+#define QUADSPI_QUIRK_NO_CLK_DISABLE	BIT(6)
+
 struct fsl_qspi_devtype_data {
 	unsigned int rxfifo;
 	unsigned int txfifo;
@@ -306,6 +311,11 @@ static inline int needs_tdh_setting(struct fsl_qspi *q)
 	return q->devtype_data->quirks & QUADSPI_QUIRK_USE_TDH_SETTING;
 }
 
+static inline int needs_clk_disable(struct fsl_qspi *q)
+{
+	return !(q->devtype_data->quirks & QUADSPI_QUIRK_NO_CLK_DISABLE);
+}
+
 /*
  * An IC bug makes it necessary to rearrange the 32-bit data.
  * Later chips, such as IMX6SLX, have fixed this bug.
@@ -536,15 +546,18 @@ static void fsl_qspi_select_mem(struct fsl_qspi *q, struct spi_device *spi,
 	if (needs_4x_clock(q))
 		rate *= 4;
 
-	fsl_qspi_clk_disable_unprep(q);
+	if (needs_clk_disable(q))
+		fsl_qspi_clk_disable_unprep(q);
 
 	ret = clk_set_rate(q->clk, rate);
 	if (ret)
 		return;
 
-	ret = fsl_qspi_clk_prep_enable(q);
-	if (ret)
-		return;
+	if (needs_clk_disable(q)) {
+		ret = fsl_qspi_clk_prep_enable(q);
+		if (ret)
+			return;
+	}
 
 	q->selected = spi_get_chipselect(spi, 0);
 
-- 
2.48.1