[PATCH] spi: spi-fsl-lpspi: limit PRESCALE bit in TCR register

[carlos.song@xxxxxxx]

From: Carlos Song <carlos.song@xxxxxxx>

Referring to the errata ERR051608 of I.MX93, LPSPI TCR[PRESCALE]
can only be configured to be 0 or 1, other values are not valid
and will cause LPSPI to not work.

Add the prescale limitation for LPSPI in I.MX93. Other platforms
are not affected.

Signed-off-by: Carlos Song <carlos.song@xxxxxxx>
---
 drivers/spi/spi-fsl-lpspi.c | 31 +++++++++++++++++++++++++++++--
 1 file changed, 29 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi-fsl-lpspi.c b/drivers/spi/spi-fsl-lpspi.c
index be261ac09df8..350c5d91d869 100644
--- a/drivers/spi/spi-fsl-lpspi.c
+++ b/drivers/spi/spi-fsl-lpspi.c
@@ -82,6 +82,10 @@
 #define TCR_RXMSK	BIT(19)
 #define TCR_TXMSK	BIT(18)
 
+struct fsl_lpspi_devtype_data {
+	u8 prescale_max;
+};
+
 struct lpspi_config {
 	u8 bpw;
 	u8 chip_select;
@@ -119,10 +123,25 @@ struct fsl_lpspi_data {
 	bool usedma;
 	struct completion dma_rx_completion;
 	struct completion dma_tx_completion;
+
+	const struct fsl_lpspi_devtype_data *devtype_data;
+};
+
+/*
+ * ERR051608 fixed or not:
+ * https://www.nxp.com/docs/en/errata/i.MX93_1P87f.pdf
+ */
+static struct fsl_lpspi_devtype_data imx93_lpspi_devtype_data = {
+	.prescale_max = 1,
+};
+
+static struct fsl_lpspi_devtype_data imx7ulp_lpspi_devtype_data = {
+	.prescale_max = 8,
 };
 
 static const struct of_device_id fsl_lpspi_dt_ids[] = {
-	{ .compatible = "fsl,imx7ulp-spi", },
+	{ .compatible = "fsl,imx7ulp-spi", .data = &imx7ulp_lpspi_devtype_data,},
+	{ .compatible = "fsl,imx93-spi", .data = &imx93_lpspi_devtype_data,},
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, fsl_lpspi_dt_ids);
@@ -297,9 +316,11 @@ static int fsl_lpspi_set_bitrate(struct fsl_lpspi_data *fsl_lpspi)
 {
 	struct lpspi_config config = fsl_lpspi->config;
 	unsigned int perclk_rate, scldiv, div;
+	u8 prescale_max;
 	u8 prescale;
 
 	perclk_rate = clk_get_rate(fsl_lpspi->clk_per);
+	prescale_max = fsl_lpspi->devtype_data->prescale_max;
 
 	if (!config.speed_hz) {
 		dev_err(fsl_lpspi->dev,
@@ -315,7 +336,7 @@ static int fsl_lpspi_set_bitrate(struct fsl_lpspi_data *fsl_lpspi)
 
 	div = DIV_ROUND_UP(perclk_rate, config.speed_hz);
 
-	for (prescale = 0; prescale < 8; prescale++) {
+	for (prescale = 0; prescale < prescale_max; prescale++) {
 		scldiv = div / (1 << prescale) - 2;
 		if (scldiv < 256) {
 			fsl_lpspi->config.prescale = prescale;
@@ -822,6 +843,7 @@ static int fsl_lpspi_init_rpm(struct fsl_lpspi_data *fsl_lpspi)
 
 static int fsl_lpspi_probe(struct platform_device *pdev)
 {
+	const struct fsl_lpspi_devtype_data *devtype_data;
 	struct fsl_lpspi_data *fsl_lpspi;
 	struct spi_controller *controller;
 	struct resource *res;
@@ -830,6 +852,10 @@ static int fsl_lpspi_probe(struct platform_device *pdev)
 	u32 temp;
 	bool is_target;
 
+	devtype_data = of_device_get_match_data(&pdev->dev);
+	if (!devtype_data)
+		return -ENODEV;
+
 	is_target = of_property_read_bool((&pdev->dev)->of_node, "spi-slave");
 	if (is_target)
 		controller = devm_spi_alloc_target(&pdev->dev,
@@ -848,6 +874,7 @@ static int fsl_lpspi_probe(struct platform_device *pdev)
 	fsl_lpspi->is_target = is_target;
 	fsl_lpspi->is_only_cs1 = of_property_read_bool((&pdev->dev)->of_node,
 						"fsl,spi-only-use-cs1-sel");
+	fsl_lpspi->devtype_data = devtype_data;
 
 	init_completion(&fsl_lpspi->xfer_done);
 
-- 
2.34.1