MLK-21150-3 drm/bridge: sec-dsim: add a new property 'pref-rate'

Add a new property 'pref-rate' support which can be used to
assign a different clock frequency for the DPHY PLL reference
clock in the dtb file. And if this property does not exist,
the default clock frequency for the reference clock will be
used. And according to the spec, the DPHY PLL reference clk
frequency should be in [6MHz, 300MHz] range.

Signed-off-by: Fancy Fang <chen.fang@nxp.com>

2 files changed, 60 insertions, 4 deletions

diff --git a/Documentation/devicetree/bindings/display/bridge/sec_dsim.txt b/Documentation/devicetree/bindings/display/bridge/sec_dsim.txt
index 9bc5e9dd2539..fd4246136d37 100644
--- a/Documentation/devicetree/bindings/display/bridge/sec_dsim.txt
+++ b/Documentation/devicetree/bindings/display/bridge/sec_dsim.txt
@@ -16,6 +16,9 @@ Required properties:
 	"pll-ref"	- DSIM PHY PLL reference clock
 - assigned-clocks:	phandles to clocks that requires initial configuration
 - assigned-clock-rates:	rates of the clocks that requires initial configuration
+- pref-clk:		Assign DPHY PLL reference clock frequency. If not exists,
+			DSIM bridge driver will use the default lock frequency
+			which is 27MHz.
 - port: 		input and output port nodes with endpoint definitions as
 			defined in Documentation/devicetree/bindings/graph.txt;
 			the input port should be connected to an encoder or a
diff --git a/drivers/gpu/drm/bridge/sec-dsim.c b/drivers/gpu/drm/bridge/sec-dsim.c
index db3c999d27d3..422ea82c4836 100644
--- a/drivers/gpu/drm/bridge/sec-dsim.c
+++ b/drivers/gpu/drm/bridge/sec-dsim.c
@@ -225,7 +225,7 @@
 #define dsim_write(dsim, val, reg)	writel(val, dsim->base + reg)
 
 /* fixed phy ref clk rate */
-#define PHY_REF_CLK		27000000
+#define PHY_REF_CLK		27000
 
 #define MAX_MAIN_HRESOL		2047
 #define MAX_MAIN_VRESOL		2047
@@ -318,6 +318,7 @@ struct sec_mipi_dsim {
 	/* kHz clocks */
 	uint32_t pix_clk;
 	uint32_t bit_clk;
+	uint32_t pref_clk;			/* phy ref clock rate in KHz */
 
 	unsigned int lanes;
 	unsigned int channel;			/* virtual channel */
@@ -440,6 +441,58 @@ static const struct dsim_hblank_par *sec_mipi_dsim_get_hblank_par(const char *na
 	return NULL;
 }
 
+static int sec_mipi_dsim_set_pref_rate(struct sec_mipi_dsim *dsim)
+{
+	int ret;
+	uint32_t rate;
+	struct device *dev = dsim->dev;
+
+	ret = of_property_read_u32(dev->of_node, "pref-rate", &rate);
+	if (ret < 0) {
+		dev_dbg(dev, "no valid rate assigned for pref clock\n");
+		dsim->pref_clk = PHY_REF_CLK;
+	} else {
+		if (unlikely(rate < 6000 || rate > 300000)) {
+			dev_warn(dev, "pref-rate get is invalid: %uKHz\n",
+				 rate);
+			dsim->pref_clk = PHY_REF_CLK;
+		} else
+			dsim->pref_clk = rate;
+	}
+
+set_rate:
+	ret = clk_set_rate(dsim->clk_pllref,
+			   ((unsigned long)dsim->pref_clk) * 1000);
+	if (ret) {
+		dev_err(dev, "failed to set pll ref clock rate\n");
+		return ret;
+	}
+
+	rate = clk_get_rate(dsim->clk_pllref) / 1000;
+	if (unlikely(!rate)) {
+		dev_err(dev, "failed to get pll ref clock rate\n");
+		return -EINVAL;
+	}
+
+	if (rate != dsim->pref_clk) {
+		if (unlikely(dsim->pref_clk == PHY_REF_CLK)) {
+			/* set default rate failed */
+			dev_err(dev, "no valid pll ref clock rate\n");
+			return -EINVAL;
+		}
+
+		dev_warn(dev, "invalid assigned rate for pref: %uKHz\n",
+			 dsim->pref_clk);
+		dev_warn(dev, "use default pref rate instead: %uKHz\n",
+			 PHY_REF_CLK);
+
+		dsim->pref_clk = PHY_REF_CLK;
+		goto set_rate;
+	}
+
+	return 0;
+}
+
 static const struct dsim_pll_pms *sec_mipi_dsim_get_pms(uint32_t bit_clk)
 {
 	int i;
@@ -1167,7 +1220,7 @@ int sec_mipi_dsim_check_pll_out(void *driver_private,
 		if (WARN_ON(!pms))
 			return -EINVAL;
 
-		ref_clk = PHY_REF_CLK / 1000;
+		ref_clk = PHY_REF_CLK;
 		/* TODO: add PMS calculate and check
 		 * Only support '1080p@60Hz' for now,
 		 * add other modes support later
@@ -1721,8 +1774,8 @@ int sec_mipi_dsim_bind(struct device *dev, struct device *master, void *data,
 
 	dev_info(dev, "version number is %#x\n", version);
 
-	/* TODO: set pll ref clock rate to be fixed with 27MHz */
-	ret = clk_set_rate(dsim->clk_pllref, PHY_REF_CLK);
+	/* set suitable rate for phy ref clock */
+	ret = sec_mipi_dsim_set_pref_rate(dsim);
 	if (ret) {
 		dev_err(dev, "failed to set pll ref clock rate\n");
 		return ret;