linux-kernel - [PATCH v3 2/4] phy: dphy: add support to calculate the timing based on hs_clk

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Date:   Thu, 22 Sep 2022 15:48:41 +0200
From:   Marco Felsch <m.felsch@...gutronix.de>
To:     mchehab@...nel.org, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, kishon@...com, vkoul@...nel.org,
        laurent.pinchart@...asonboard.com, sakari.ailus@...ux.intel.com,
        jacopo@...ndi.org, hverkuil@...all.nl
Cc:     linux-phy@...ts.infradead.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, linux-media@...r.kernel.org,
        kernel@...gutronix.de
Subject: [PATCH v3 2/4] phy: dphy: add support to calculate the timing based on hs_clk_rate

For MIPI-CSI sender use-case it is common to specify the allowed
link-frequencies which should be used for the MIPI link and is
half the hs-clock rate.

This commit adds a helper to calculate the D-PHY timing based on the
hs-clock rate so we don't need to calculate the timings within the
driver.

Signed-off-by: Marco Felsch <m.felsch@...gutronix.de>
Acked-by: Vinod Koul <vkoul@...nel.org>
---
Changelog:

v2:
- added Vinod Koul a-b
---
 drivers/phy/phy-core-mipi-dphy.c  | 22 ++++++++++++++++++----
 include/linux/phy/phy-mipi-dphy.h |  3 +++
 2 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/drivers/phy/phy-core-mipi-dphy.c b/drivers/phy/phy-core-mipi-dphy.c
index ba365bc77407..f4956a417a47 100644
--- a/drivers/phy/phy-core-mipi-dphy.c
+++ b/drivers/phy/phy-core-mipi-dphy.c
@@ -20,16 +20,18 @@
 static int phy_mipi_dphy_calc_config(unsigned long pixel_clock,
 				     unsigned int bpp,
 				     unsigned int lanes,
+				     unsigned long long hs_clk_rate,
 				     struct phy_configure_opts_mipi_dphy *cfg)
 {
-	unsigned long long hs_clk_rate;
 	unsigned long long ui;
 
 	if (!cfg)
 		return -EINVAL;
 
-	hs_clk_rate = pixel_clock * bpp;
-	do_div(hs_clk_rate, lanes);
+	if (!hs_clk_rate) {
+		hs_clk_rate = pixel_clock * bpp;
+		do_div(hs_clk_rate, lanes);
+	}
 
 	ui = ALIGN(PSEC_PER_SEC, hs_clk_rate);
 	do_div(ui, hs_clk_rate);
@@ -81,11 +83,23 @@ int phy_mipi_dphy_get_default_config(unsigned long pixel_clock,
 				     unsigned int lanes,
 				     struct phy_configure_opts_mipi_dphy *cfg)
 {
-	return phy_mipi_dphy_calc_config(pixel_clock, bpp, lanes, cfg);
+	return phy_mipi_dphy_calc_config(pixel_clock, bpp, lanes, 0, cfg);
 
 }
 EXPORT_SYMBOL(phy_mipi_dphy_get_default_config);
 
+int phy_mipi_dphy_get_default_config_for_hsclk(unsigned long long hs_clk_rate,
+					       unsigned int lanes,
+					       struct phy_configure_opts_mipi_dphy *cfg)
+{
+	if (!hs_clk_rate)
+		return -EINVAL;
+
+	return phy_mipi_dphy_calc_config(0, 0, lanes, hs_clk_rate, cfg);
+
+}
+EXPORT_SYMBOL(phy_mipi_dphy_get_default_config_for_hsclk);
+
 /*
  * Validate D-PHY configuration according to MIPI D-PHY specification
  * (v1.2, Section Section 6.9 "Global Operation Timing Parameters").
diff --git a/include/linux/phy/phy-mipi-dphy.h b/include/linux/phy/phy-mipi-dphy.h
index a877ffee845d..1ac128d78dfe 100644
--- a/include/linux/phy/phy-mipi-dphy.h
+++ b/include/linux/phy/phy-mipi-dphy.h
@@ -279,6 +279,9 @@ int phy_mipi_dphy_get_default_config(unsigned long pixel_clock,
 				     unsigned int bpp,
 				     unsigned int lanes,
 				     struct phy_configure_opts_mipi_dphy *cfg);
+int phy_mipi_dphy_get_default_config_for_hsclk(unsigned long long hs_clk_rate,
+					       unsigned int lanes,
+					       struct phy_configure_opts_mipi_dphy *cfg);
 int phy_mipi_dphy_config_validate(struct phy_configure_opts_mipi_dphy *cfg);
 
 #endif /* __PHY_MIPI_DPHY_H_ */
-- 
2.30.2