[PATCH 1/5] spi: bcm-qspi: Add support for setting BSPI clock

[Mark Tomlinson <mark.tomlinson@xxxxxxxxxxxxxxxxxxx>]

On iProc devices (unlike previous BCM SoCs) the clock rate of the SPI
can be set. This patch adds the appropriate code for setting that.

Reviewed-by: Callum Sinclair <callum.sinclair@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Chris Packham <chris.packham@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Mark Tomlinson <mark.tomlinson@xxxxxxxxxxxxxxxxxxx>
---
 drivers/spi/spi-bcm-qspi.c | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/drivers/spi/spi-bcm-qspi.c b/drivers/spi/spi-bcm-qspi.c
index 681d09085175..8fc5b9b3757b 100644
--- a/drivers/spi/spi-bcm-qspi.c
+++ b/drivers/spi/spi-bcm-qspi.c
@@ -117,6 +117,13 @@
 
 #define MSPI_MSPI_STATUS_SPIF			BIT(0)
 
+#define CRU_CTRL_REG				0x0
+#define QSPI_CLK_SEL_25M			0x00
+#define QSPI_CLK_SEL_50M			0x02
+#define QSPI_CLK_SEL_31M25			0x04
+#define QSPI_CLK_SEL_62M5			0x06
+#define QSPI_CLK_SEL_MASK			0x06
+
 #define INTR_BASE_BIT_SHIFT			0x02
 #define INTR_COUNT				0x07
 
@@ -170,6 +177,7 @@ enum base_type {
 	MSPI,
 	BSPI,
 	CHIP_SELECT,
+	CRU_CTRL,
 	BASEMAX,
 };
 
@@ -625,6 +633,7 @@ static void bcm_qspi_update_parms(struct bcm_qspi *qspi,
 static int bcm_qspi_setup(struct spi_device *spi)
 {
 	struct bcm_qspi_parms *xp;
+	struct bcm_qspi *qspi = spi_master_get_devdata(spi->master);
 
 	if (spi->bits_per_word > 16)
 		return -EINVAL;
@@ -639,6 +648,21 @@ static int bcm_qspi_setup(struct spi_device *spi)
 	xp->speed_hz = spi->max_speed_hz;
 	xp->mode = spi->mode;
 
+	if (qspi->base[CRU_CTRL]) {
+		u32 tmp = bcm_qspi_read(qspi, CRU_CTRL, CRU_CTRL_REG);
+
+		/* Set BSPI clock rate */
+		tmp &= ~QSPI_CLK_SEL_MASK;
+		if (spi->max_speed_hz >= 62500000)
+			tmp |= QSPI_CLK_SEL_62M5;
+		else if (spi->max_speed_hz >= 50000000)
+			tmp |= QSPI_CLK_SEL_50M;
+		else if (spi->max_speed_hz >= 31250000)
+			tmp |= QSPI_CLK_SEL_31M25;
+		/* default is 25MHz */
+		bcm_qspi_write(qspi, CRU_CTRL, CRU_CTRL_REG, tmp);
+	}
+
 	if (spi->bits_per_word)
 		xp->bits_per_word = spi->bits_per_word;
 	else
@@ -1459,6 +1483,16 @@ int bcm_qspi_probe(struct platform_device *pdev,
 		qspi->soc_intc = NULL;
 	}
 
+	/* iProc BSPI clock is set through CRU control */
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "cru_ctrl");
+	if (res) {
+		qspi->base[CRU_CTRL] = devm_ioremap_resource(dev, res);
+		if (IS_ERR(qspi->base[CRU_CTRL])) {
+			ret = PTR_ERR(qspi->base[CRU_CTRL]);
+			goto qspi_probe_err;
+		}
+	}
+
 	ret = clk_prepare_enable(qspi->clk);
 	if (ret) {
 		dev_err(dev, "failed to prepare clock\n");
-- 
2.27.0