spi: s3c64xx: support custom value of internal clock divider

Modern exynos SoCs such as Exynos Auto v9 have different internal clock
divider, for example "4". To support this internal value, this adds
clk_div of the s3c64xx_spi_port_config and assign "2" as the default
value to existing s3c64xx_spi_port_config.
Signed-off-by: Chanho Park <chanho61.park@samsung.com>
Reviewed-by: Andi Shyti <andi@etezian.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220629102304.65712-3-chanho61.park@samsung.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-s3c64xx.c

@@ -131,6 +131,7 @@ struct s3c64xx_spi_dma_data {
  * @fifo_lvl_mask: Bit-mask for {TX|RX}_FIFO_LVL bits in SPI_STATUS register.
  * @rx_lvl_offset: Bit offset of RX_FIFO_LVL bits in SPI_STATUS regiter.
  * @tx_st_done: Bit offset of TX_DONE bit in SPI_STATUS regiter.
+ * @clk_div: Internal clock divider
  * @quirks: Bitmask of known quirks
  * @high_speed: True, if the controller supports HIGH_SPEED_EN bit.
  * @clk_from_cmu: True, if the controller does not include a clock mux and
@@ -148,6 +149,7 @@ struct s3c64xx_spi_port_config {
 	int	rx_lvl_offset;
 	int	tx_st_done;
 	int	quirks;
+	int	clk_div;
 	bool	high_speed;
 	bool	clk_from_cmu;
 	bool	clk_ioclk;
@@ -620,6 +622,7 @@ static int s3c64xx_spi_config(struct s3c64xx_spi_driver_data *sdd)
 	void __iomem *regs = sdd->regs;
 	int ret;
 	u32 val;
+	int div = sdd->port_conf->clk_div;
 
 	/* Disable Clock */
 	if (!sdd->port_conf->clk_from_cmu) {
@@ -668,16 +671,15 @@ static int s3c64xx_spi_config(struct s3c64xx_spi_driver_data *sdd)
 	writel(val, regs + S3C64XX_SPI_MODE_CFG);
 
 	if (sdd->port_conf->clk_from_cmu) {
-		/* The src_clk clock is divided internally by 2 */
-		ret = clk_set_rate(sdd->src_clk, sdd->cur_speed * 2);
+		ret = clk_set_rate(sdd->src_clk, sdd->cur_speed * div);
 		if (ret)
 			return ret;
-		sdd->cur_speed = clk_get_rate(sdd->src_clk) / 2;
+		sdd->cur_speed = clk_get_rate(sdd->src_clk) / div;
 	} else {
 		/* Configure Clock */
 		val = readl(regs + S3C64XX_SPI_CLK_CFG);
 		val &= ~S3C64XX_SPI_PSR_MASK;
-		val |= ((clk_get_rate(sdd->src_clk) / sdd->cur_speed / 2 - 1)
+		val |= ((clk_get_rate(sdd->src_clk) / sdd->cur_speed / div - 1)
 				& S3C64XX_SPI_PSR_MASK);
 		writel(val, regs + S3C64XX_SPI_CLK_CFG);
 
@@ -871,6 +873,7 @@ static int s3c64xx_spi_setup(struct spi_device *spi)
 	struct s3c64xx_spi_csinfo *cs = spi->controller_data;
 	struct s3c64xx_spi_driver_data *sdd;
 	int err;
+	int div;
 
 	sdd = spi_master_get_devdata(spi->master);
 	if (spi->dev.of_node) {
@@ -889,22 +892,24 @@ static int s3c64xx_spi_setup(struct spi_device *spi)
 
 	pm_runtime_get_sync(&sdd->pdev->dev);
 
+	div = sdd->port_conf->clk_div;
+
 	/* Check if we can provide the requested rate */
 	if (!sdd->port_conf->clk_from_cmu) {
 		u32 psr, speed;
 
 		/* Max possible */
-		speed = clk_get_rate(sdd->src_clk) / 2 / (0 + 1);
+		speed = clk_get_rate(sdd->src_clk) / div / (0 + 1);
 
 		if (spi->max_speed_hz > speed)
 			spi->max_speed_hz = speed;
 
-		psr = clk_get_rate(sdd->src_clk) / 2 / spi->max_speed_hz - 1;
+		psr = clk_get_rate(sdd->src_clk) / div / spi->max_speed_hz - 1;
 		psr &= S3C64XX_SPI_PSR_MASK;
 		if (psr == S3C64XX_SPI_PSR_MASK)
 			psr--;
 
-		speed = clk_get_rate(sdd->src_clk) / 2 / (psr + 1);
+		speed = clk_get_rate(sdd->src_clk) / div / (psr + 1);
 		if (spi->max_speed_hz < speed) {
 			if (psr+1 < S3C64XX_SPI_PSR_MASK) {
 				psr++;
@@ -914,7 +919,7 @@ static int s3c64xx_spi_setup(struct spi_device *spi)
 			}
 		}
 
-		speed = clk_get_rate(sdd->src_clk) / 2 / (psr + 1);
+		speed = clk_get_rate(sdd->src_clk) / div / (psr + 1);
 		if (spi->max_speed_hz >= speed) {
 			spi->max_speed_hz = speed;
 		} else {
@@ -1396,6 +1401,7 @@ static const struct s3c64xx_spi_port_config s3c2443_spi_port_config = {
 	.fifo_lvl_mask	= { 0x7f },
 	.rx_lvl_offset	= 13,
 	.tx_st_done	= 21,
+	.clk_div	= 2,
 	.high_speed	= true,
 };
 
@@ -1403,12 +1409,14 @@ static const struct s3c64xx_spi_port_config s3c6410_spi_port_config = {
 	.fifo_lvl_mask	= { 0x7f, 0x7F },
 	.rx_lvl_offset	= 13,
 	.tx_st_done	= 21,
+	.clk_div	= 2,
 };
 
 static const struct s3c64xx_spi_port_config s5pv210_spi_port_config = {
 	.fifo_lvl_mask	= { 0x1ff, 0x7F },
 	.rx_lvl_offset	= 15,
 	.tx_st_done	= 25,
+	.clk_div	= 2,
 	.high_speed	= true,
 };
 
@@ -1416,6 +1424,7 @@ static const struct s3c64xx_spi_port_config exynos4_spi_port_config = {
 	.fifo_lvl_mask	= { 0x1ff, 0x7F, 0x7F },
 	.rx_lvl_offset	= 15,
 	.tx_st_done	= 25,
+	.clk_div	= 2,
 	.high_speed	= true,
 	.clk_from_cmu	= true,
 	.quirks		= S3C64XX_SPI_QUIRK_CS_AUTO,
@@ -1425,6 +1434,7 @@ static const struct s3c64xx_spi_port_config exynos7_spi_port_config = {
 	.fifo_lvl_mask	= { 0x1ff, 0x7F, 0x7F, 0x7F, 0x7F, 0x1ff},
 	.rx_lvl_offset	= 15,
 	.tx_st_done	= 25,
+	.clk_div	= 2,
 	.high_speed	= true,
 	.clk_from_cmu	= true,
 	.quirks		= S3C64XX_SPI_QUIRK_CS_AUTO,
@@ -1434,6 +1444,7 @@ static const struct s3c64xx_spi_port_config exynos5433_spi_port_config = {
 	.fifo_lvl_mask	= { 0x1ff, 0x7f, 0x7f, 0x7f, 0x7f, 0x1ff},
 	.rx_lvl_offset	= 15,
 	.tx_st_done	= 25,
+	.clk_div	= 2,
 	.high_speed	= true,
 	.clk_from_cmu	= true,
 	.clk_ioclk	= true,
@@ -1444,6 +1455,7 @@ static const struct s3c64xx_spi_port_config fsd_spi_port_config = {
 	.fifo_lvl_mask	= { 0x7f, 0x7f, 0x7f, 0x7f, 0x7f},
 	.rx_lvl_offset	= 15,
 	.tx_st_done	= 25,
+	.clk_div	= 2,
 	.high_speed	= true,
 	.clk_from_cmu	= true,
 	.clk_ioclk	= false,