[PATCH 2/4] dmaengine: imx-sdma: Add clock ratio 1:1 check

[Angus Ainslie (Purism)]

On imx8mq B0 chip, AHB/SDMA clock ratio 2:1 can't be supported,
since SDMA clock ratio has to be increased to 250Mhz, AHB can't reach
to 500Mhz, so use 1:1 instead.

To limit this change to the imx8mq for now this patch also adds an
im8mq-sdma compatible string.

Signed-off-by: Angus Ainslie (Purism) <angus@xxxxxxxx>
---
 drivers/dma/imx-sdma.c | 31 +++++++++++++++++++++++++++----
 1 file changed, 27 insertions(+), 4 deletions(-)

diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
index 7fae4bf885d5..99d9f431ae2c 100644
--- a/drivers/dma/imx-sdma.c
+++ b/drivers/dma/imx-sdma.c
@@ -419,6 +419,7 @@ struct sdma_driver_data {
 	int chnenbl0;
 	int num_events;
 	struct sdma_script_start_addrs	*script_addrs;
+	bool check_ratio;
 };
 
 struct sdma_engine {
@@ -441,6 +442,8 @@ struct sdma_engine {
 	unsigned int			irq;
 	dma_addr_t			bd0_phys;
 	struct sdma_buffer_descriptor	*bd0;
+	/* clock ratio for AHB:SDMA core. 1:1 is 1, 2:1 is 0*/
+	bool				clk_ratio;
 };
 
 static int sdma_config_write(struct dma_chan *chan,
@@ -555,6 +558,13 @@ static struct sdma_driver_data sdma_imx7d = {
 	.script_addrs = &sdma_script_imx7d,
 };
 
+static struct sdma_driver_data sdma_imx8mq = {
+	.chnenbl0 = SDMA_CHNENBL0_IMX35,
+	.num_events = 48,
+	.script_addrs = &sdma_script_imx7d,
+	.check_ratio = 1,
+};
+
 static const struct platform_device_id sdma_devtypes[] = {
 	{
 		.name = "imx25-sdma",
@@ -577,6 +587,9 @@ static const struct platform_device_id sdma_devtypes[] = {
 	}, {
 		.name = "imx7d-sdma",
 		.driver_data = (unsigned long)&sdma_imx7d,
+	}, {
+		.name = "imx8mq-sdma",
+		.driver_data = (unsigned long)&sdma_imx8mq,
 	}, {
 		/* sentinel */
 	}
@@ -591,6 +604,7 @@ static const struct of_device_id sdma_dt_ids[] = {
 	{ .compatible = "fsl,imx31-sdma", .data = &sdma_imx31, },
 	{ .compatible = "fsl,imx25-sdma", .data = &sdma_imx25, },
 	{ .compatible = "fsl,imx7d-sdma", .data = &sdma_imx7d, },
+	{ .compatible = "fsl,imx8mq-sdma", .data = &sdma_imx8mq, },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, sdma_dt_ids);
@@ -663,8 +677,11 @@ static int sdma_run_channel0(struct sdma_engine *sdma)
 		dev_err(sdma->dev, "Timeout waiting for CH0 ready\n");
 
 	/* Set bits of CONFIG register with dynamic context switching */
-	if (readl(sdma->regs + SDMA_H_CONFIG) == 0)
-		writel_relaxed(SDMA_H_CONFIG_CSM, sdma->regs + SDMA_H_CONFIG);
+	reg = readl(sdma->regs + SDMA_H_CONFIG);
+	if ((reg & SDMA_H_CONFIG_CSM) == 0) {
+		reg |= SDMA_H_CONFIG_CSM;
+		writel_relaxed(reg, sdma->regs + SDMA_H_CONFIG);
+	}
 
 	return ret;
 }
@@ -1847,6 +1864,10 @@ static int sdma_init(struct sdma_engine *sdma)
 	if (ret)
 		goto disable_clk_ipg;
 
+	if (sdma->drvdata->check_ratio &&
+	    (clk_get_rate(sdma->clk_ahb) == clk_get_rate(sdma->clk_ipg)))
+		sdma->clk_ratio = 1;
+
 	/* Be sure SDMA has not started yet */
 	writel_relaxed(0, sdma->regs + SDMA_H_C0PTR);
 
@@ -1887,8 +1908,10 @@ static int sdma_init(struct sdma_engine *sdma)
 	writel_relaxed(0x4050, sdma->regs + SDMA_CHN0ADDR);
 
 	/* Set bits of CONFIG register but with static context switching */
-	/* FIXME: Check whether to set ACR bit depending on clock ratios */
-	writel_relaxed(0, sdma->regs + SDMA_H_CONFIG);
+	if (sdma->clk_ratio)
+		writel_relaxed(SDMA_H_CONFIG_ACR, sdma->regs + SDMA_H_CONFIG);
+	else
+		writel_relaxed(0, sdma->regs + SDMA_H_CONFIG);
 
 	writel_relaxed(ccb_phys, sdma->regs + SDMA_H_C0PTR);
 
-- 
2.17.1