drm/msm/dsi: Set up link clocks for DSIv2

DSIv2 (DSI on older A family chips) has slightly different link clock
requirements.

First, we have an extra clock called src_clk (with a dedicated RCG).
This is required by the DSI controller to process the pixel data
coming from MDP. It needs to be set at the rate "pclk * bytes_per_pixel".

We also need to explicitly configure esc_clk. On DSI6G chips, we don't
need to set a rate to esc_clk because its RCG is always sourced from
crystal clock (19.2 Mhz in all cases), which is within the escape clock
frequency range in the mipi DSI spec. For chips with DSIv2, the crystal
clock rate may not be within the required range (27Mhz on APQ8064).
Therefore, we derive it from the DSI byte clock. We calculate an esc_clck
rate that is within the mipi spec and also divisible by the byte clock
rate.

When setting rate and enabling the link clocks, we make sure that byte_clk
is configured before esc_clk, and src_clk before pixel_clk. We create two
different link_enable funcs for DSI6G and DSIv2 since the sequences are
different.

We also obtain two extra source clocks (dsi_src_clk and esc_src_clk) and
set their parent to the clocks provided by DSI PLL.
Signed-off-by: Archit Taneja <architt@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>

drivers/gpu/drm/msm/dsi/dsi_host.c

@@ -113,6 +113,14 @@ struct msm_dsi_host {
 	struct clk *pixel_clk_src;
 
 	u32 byte_clk_rate;
+	u32 esc_clk_rate;
+
+	/* DSI v2 specific clocks */
+	struct clk *src_clk;
+	struct clk *esc_clk_src;
+	struct clk *dsi_clk_src;
+
+	u32 src_clk_rate;
 
 	struct gpio_desc *disp_en_gpio;
 	struct gpio_desc *te_gpio;
@@ -318,7 +326,8 @@ static int dsi_regulator_init(struct msm_dsi_host *msm_host)
 static int dsi_clk_init(struct msm_dsi_host *msm_host)
 {
 	struct device *dev = &msm_host->pdev->dev;
-	const struct msm_dsi_config *cfg = msm_host->cfg_hnd->cfg;
+	const struct msm_dsi_cfg_handler *cfg_hnd = msm_host->cfg_hnd;
+	const struct msm_dsi_config *cfg = cfg_hnd->cfg;
 	int i, ret = 0;
 
 	/* get bus clocks */
@@ -372,8 +381,34 @@ static int dsi_clk_init(struct msm_dsi_host *msm_host)
 	if (!msm_host->pixel_clk_src) {
 		ret = -ENODEV;
 		pr_err("%s: can't find pixel_clk_src. ret=%d\n", __func__, ret);
+		goto exit;
 	}
 
+	if (cfg_hnd->major == MSM_DSI_VER_MAJOR_V2) {
+		msm_host->src_clk = devm_clk_get(dev, "src_clk");
+		if (IS_ERR(msm_host->src_clk)) {
+			ret = PTR_ERR(msm_host->src_clk);
+			pr_err("%s: can't find dsi_src_clk. ret=%d\n",
+				__func__, ret);
+			msm_host->src_clk = NULL;
+			goto exit;
+		}
+
+		msm_host->esc_clk_src = clk_get_parent(msm_host->esc_clk);
+		if (!msm_host->esc_clk_src) {
+			ret = -ENODEV;
+			pr_err("%s: can't get esc_clk_src. ret=%d\n",
+				__func__, ret);
+			goto exit;
+		}
+
+		msm_host->dsi_clk_src = clk_get_parent(msm_host->src_clk);
+		if (!msm_host->dsi_clk_src) {
+			ret = -ENODEV;
+			pr_err("%s: can't get dsi_clk_src. ret=%d\n",
+				__func__, ret);
+		}
+	}
 exit:
 	return ret;
 }
@@ -413,7 +448,7 @@ static void dsi_bus_clk_disable(struct msm_dsi_host *msm_host)
 		clk_disable_unprepare(msm_host->bus_clks[i]);
 }
 
-static int dsi_link_clk_enable(struct msm_dsi_host *msm_host)
+static int dsi_link_clk_enable_6g(struct msm_dsi_host *msm_host)
 {
 	int ret;
 
@@ -460,11 +495,98 @@ static int dsi_link_clk_enable(struct msm_dsi_host *msm_host)
 	return ret;
 }
 
+static int dsi_link_clk_enable_v2(struct msm_dsi_host *msm_host)
+{
+	int ret;
+
+	DBG("Set clk rates: pclk=%d, byteclk=%d, esc_clk=%d, dsi_src_clk=%d",
+		msm_host->mode->clock, msm_host->byte_clk_rate,
+		msm_host->esc_clk_rate, msm_host->src_clk_rate);
+
+	ret = clk_set_rate(msm_host->byte_clk, msm_host->byte_clk_rate);
+	if (ret) {
+		pr_err("%s: Failed to set rate byte clk, %d\n", __func__, ret);
+		goto error;
+	}
+
+	ret = clk_set_rate(msm_host->esc_clk, msm_host->esc_clk_rate);
+	if (ret) {
+		pr_err("%s: Failed to set rate esc clk, %d\n", __func__, ret);
+		goto error;
+	}
+
+	ret = clk_set_rate(msm_host->src_clk, msm_host->src_clk_rate);
+	if (ret) {
+		pr_err("%s: Failed to set rate src clk, %d\n", __func__, ret);
+		goto error;
+	}
+
+	ret = clk_set_rate(msm_host->pixel_clk, msm_host->mode->clock * 1000);
+	if (ret) {
+		pr_err("%s: Failed to set rate pixel clk, %d\n", __func__, ret);
+		goto error;
+	}
+
+	ret = clk_prepare_enable(msm_host->byte_clk);
+	if (ret) {
+		pr_err("%s: Failed to enable dsi byte clk\n", __func__);
+		goto error;
+	}
+
+	ret = clk_prepare_enable(msm_host->esc_clk);
+	if (ret) {
+		pr_err("%s: Failed to enable dsi esc clk\n", __func__);
+		goto esc_clk_err;
+	}
+
+	ret = clk_prepare_enable(msm_host->src_clk);
+	if (ret) {
+		pr_err("%s: Failed to enable dsi src clk\n", __func__);
+		goto src_clk_err;
+	}
+
+	ret = clk_prepare_enable(msm_host->pixel_clk);
+	if (ret) {
+		pr_err("%s: Failed to enable dsi pixel clk\n", __func__);
+		goto pixel_clk_err;
+	}
+
+	return 0;
+
+pixel_clk_err:
+	clk_disable_unprepare(msm_host->src_clk);
+src_clk_err:
+	clk_disable_unprepare(msm_host->esc_clk);
+esc_clk_err:
+	clk_disable_unprepare(msm_host->byte_clk);
+error:
+	return ret;
+}
+
+static int dsi_link_clk_enable(struct msm_dsi_host *msm_host)
+{
+	const struct msm_dsi_cfg_handler *cfg_hnd = msm_host->cfg_hnd;
+
+	if (cfg_hnd->major == MSM_DSI_VER_MAJOR_6G)
+		return dsi_link_clk_enable_6g(msm_host);
+	else
+		return dsi_link_clk_enable_v2(msm_host);
+}
+
 static void dsi_link_clk_disable(struct msm_dsi_host *msm_host)
 {
+	const struct msm_dsi_cfg_handler *cfg_hnd = msm_host->cfg_hnd;
+
+	if (cfg_hnd->major == MSM_DSI_VER_MAJOR_6G) {
 		clk_disable_unprepare(msm_host->esc_clk);
 		clk_disable_unprepare(msm_host->pixel_clk);
 		clk_disable_unprepare(msm_host->byte_clk);
+	} else {
+		clk_disable_unprepare(msm_host->pixel_clk);
+		clk_disable_unprepare(msm_host->src_clk);
+		clk_disable_unprepare(msm_host->esc_clk);
+		clk_disable_unprepare(msm_host->byte_clk);
+	}
 }
 
 static int dsi_clk_ctrl(struct msm_dsi_host *msm_host, bool enable)
@@ -499,6 +621,7 @@ static int dsi_clk_ctrl(struct msm_dsi_host *msm_host, bool enable)
 static int dsi_calc_clk_rate(struct msm_dsi_host *msm_host)
 {
 	struct drm_display_mode *mode = msm_host->mode;
+	const struct msm_dsi_cfg_handler *cfg_hnd = msm_host->cfg_hnd;
 	u8 lanes = msm_host->lanes;
 	u32 bpp = dsi_get_bpp(msm_host->format);
 	u32 pclk_rate;
@@ -518,6 +641,47 @@ static int dsi_calc_clk_rate(struct msm_dsi_host *msm_host)
 
 	DBG("pclk=%d, bclk=%d", pclk_rate, msm_host->byte_clk_rate);
 
+	msm_host->esc_clk_rate = clk_get_rate(msm_host->esc_clk);
+
+	if (cfg_hnd->major == MSM_DSI_VER_MAJOR_V2) {
+		unsigned int esc_mhz, esc_div;
+		unsigned long byte_mhz;
+
+		msm_host->src_clk_rate = (pclk_rate * bpp) / 8;
+
+		/*
+		 * esc clock is byte clock followed by a 4 bit divider,
+		 * we need to find an escape clock frequency within the
+		 * mipi DSI spec range within the maximum divider limit
+		 * We iterate here between an escape clock frequencey
+		 * between 20 Mhz to 5 Mhz and pick up the first one
+		 * that can be supported by our divider
+		 */
+
+		byte_mhz = msm_host->byte_clk_rate / 1000000;
+
+		for (esc_mhz = 20; esc_mhz >= 5; esc_mhz--) {
+			esc_div = DIV_ROUND_UP(byte_mhz, esc_mhz);
+
+			/*
+			 * TODO: Ideally, we shouldn't know what sort of divider
+			 * is available in mmss_cc, we're just assuming that
+			 * it'll always be a 4 bit divider. Need to come up with
+			 * a better way here.
+			 */
+			if (esc_div >= 1 && esc_div <= 16)
+				break;
+		}
+
+		if (esc_mhz < 5)
+			return -EINVAL;
+
+		msm_host->esc_clk_rate = msm_host->byte_clk_rate / esc_div;
+
+		DBG("esc=%d, src=%d", msm_host->esc_clk_rate,
+			msm_host->src_clk_rate);
+	}
+
 	return 0;
 }
 
@@ -1750,6 +1914,7 @@ int msm_dsi_host_set_src_pll(struct mipi_dsi_host *host,
 	struct msm_dsi_pll *src_pll)
 {
 	struct msm_dsi_host *msm_host = to_msm_dsi_host(host);
+	const struct msm_dsi_cfg_handler *cfg_hnd = msm_host->cfg_hnd;
 	struct clk *byte_clk_provider, *pixel_clk_provider;
 	int ret;
 
@@ -1775,6 +1940,22 @@ int msm_dsi_host_set_src_pll(struct mipi_dsi_host *host,
 		goto exit;
 	}
 
+	if (cfg_hnd->major == MSM_DSI_VER_MAJOR_V2) {
+		ret = clk_set_parent(msm_host->dsi_clk_src, pixel_clk_provider);
+		if (ret) {
+			pr_err("%s: can't set parent to dsi_clk_src. ret=%d\n",
+				__func__, ret);
+			goto exit;
+		}
+
+		ret = clk_set_parent(msm_host->esc_clk_src, byte_clk_provider);
+		if (ret) {
+			pr_err("%s: can't set parent to esc_clk_src. ret=%d\n",
+				__func__, ret);
+			goto exit;
+		}
+	}
+
 exit:
 	return ret;
 }
@@ -1846,7 +2027,7 @@ int msm_dsi_host_power_on(struct mipi_dsi_host *host)
 	dsi_phy_sw_reset(msm_host);
 	ret = msm_dsi_manager_phy_enable(msm_host->id,
 					msm_host->byte_clk_rate * 8,
-					clk_get_rate(msm_host->esc_clk),
+					msm_host->esc_clk_rate,
 					&clk_pre, &clk_post);
 	dsi_bus_clk_disable(msm_host);
 	if (ret) {