phy: Add Cadence D-PHY support

Cadence has designed a D-PHY that can be used by the, currently in tree,
DSI bridge (DRM), CSI Transceiver and CSI Receiver (v4l2) drivers.

Only the DSI driver has an ad-hoc driver for that phy at the moment, while
the v4l2 drivers are completely missing any phy support. In order to make
that phy support available to all these drivers, without having to
duplicate that code three times, let's create a generic phy framework
driver.
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

drivers/phy/cadence/Kconfig

 #
 # Phy drivers for Cadence PHYs
 #
+
 config PHY_CADENCE_DP
 	tristate "Cadence MHDP DisplayPort PHY driver"
 	depends on OF
@@ -9,9 +10,19 @@ config PHY_CADENCE_DP
 	help
 	  Support for Cadence MHDP DisplayPort PHY.
 
+config PHY_CADENCE_DPHY
+	tristate "Cadence D-PHY Support"
+	depends on HAS_IOMEM && OF
+	select GENERIC_PHY
+	select GENERIC_PHY_MIPI_DPHY
+	help
+	  Choose this option if you have a Cadence D-PHY in your
+	  system. If M is selected, the module will be called
+	  cdns-dphy.
+
 config PHY_CADENCE_SIERRA
 	tristate "Cadence Sierra PHY Driver"
 	depends on OF && HAS_IOMEM && RESET_CONTROLLER
 	select GENERIC_PHY
 	help
-	  Enable this to support the Cadence Sierra PHY driver
\ No newline at end of file
+	  Enable this to support the Cadence Sierra PHY driver

drivers/phy/cadence/Makefile

 obj-$(CONFIG_PHY_CADENCE_DP)	+= phy-cadence-dp.o
+obj-$(CONFIG_PHY_CADENCE_DPHY)	+= cdns-dphy.o
 obj-$(CONFIG_PHY_CADENCE_SIERRA)	+= phy-cadence-sierra.o

drivers/phy/cadence/cdns-dphy.c

+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright: 2017-2018 Cadence Design Systems, Inc.
+ */
+
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/reset.h>
+
+#include <linux/phy/phy.h>
+#include <linux/phy/phy-mipi-dphy.h>
+
+#define REG_WAKEUP_TIME_NS		800
+#define DPHY_PLL_RATE_HZ		108000000
+
+/* DPHY registers */
+#define DPHY_PMA_CMN(reg)		(reg)
+#define DPHY_PMA_LCLK(reg)		(0x100 + (reg))
+#define DPHY_PMA_LDATA(lane, reg)	(0x200 + ((lane) * 0x100) + (reg))
+#define DPHY_PMA_RCLK(reg)		(0x600 + (reg))
+#define DPHY_PMA_RDATA(lane, reg)	(0x700 + ((lane) * 0x100) + (reg))
+#define DPHY_PCS(reg)			(0xb00 + (reg))
+
+#define DPHY_CMN_SSM			DPHY_PMA_CMN(0x20)
+#define DPHY_CMN_SSM_EN			BIT(0)
+#define DPHY_CMN_TX_MODE_EN		BIT(9)
+
+#define DPHY_CMN_PWM			DPHY_PMA_CMN(0x40)
+#define DPHY_CMN_PWM_DIV(x)		((x) << 20)
+#define DPHY_CMN_PWM_LOW(x)		((x) << 10)
+#define DPHY_CMN_PWM_HIGH(x)		(x)
+
+#define DPHY_CMN_FBDIV			DPHY_PMA_CMN(0x4c)
+#define DPHY_CMN_FBDIV_VAL(low, high)	(((high) << 11) | ((low) << 22))
+#define DPHY_CMN_FBDIV_FROM_REG		(BIT(10) | BIT(21))
+
+#define DPHY_CMN_OPIPDIV		DPHY_PMA_CMN(0x50)
+#define DPHY_CMN_IPDIV_FROM_REG		BIT(0)
+#define DPHY_CMN_IPDIV(x)		((x) << 1)
+#define DPHY_CMN_OPDIV_FROM_REG		BIT(6)
+#define DPHY_CMN_OPDIV(x)		((x) << 7)
+
+#define DPHY_PSM_CFG			DPHY_PCS(0x4)
+#define DPHY_PSM_CFG_FROM_REG		BIT(0)
+#define DPHY_PSM_CLK_DIV(x)		((x) << 1)
+
+#define DSI_HBP_FRAME_OVERHEAD		12
+#define DSI_HSA_FRAME_OVERHEAD		14
+#define DSI_HFP_FRAME_OVERHEAD		6
+#define DSI_HSS_VSS_VSE_FRAME_OVERHEAD	4
+#define DSI_BLANKING_FRAME_OVERHEAD	6
+#define DSI_NULL_FRAME_OVERHEAD		6
+#define DSI_EOT_PKT_SIZE		4
+
+struct cdns_dphy_cfg {
+	u8 pll_ipdiv;
+	u8 pll_opdiv;
+	u16 pll_fbdiv;
+	unsigned int nlanes;
+};
+
+enum cdns_dphy_clk_lane_cfg {
+	DPHY_CLK_CFG_LEFT_DRIVES_ALL = 0,
+	DPHY_CLK_CFG_LEFT_DRIVES_RIGHT = 1,
+	DPHY_CLK_CFG_LEFT_DRIVES_LEFT = 2,
+	DPHY_CLK_CFG_RIGHT_DRIVES_ALL = 3,
+};
+
+struct cdns_dphy;
+struct cdns_dphy_ops {
+	int (*probe)(struct cdns_dphy *dphy);
+	void (*remove)(struct cdns_dphy *dphy);
+	void (*set_psm_div)(struct cdns_dphy *dphy, u8 div);
+	void (*set_clk_lane_cfg)(struct cdns_dphy *dphy,
+				 enum cdns_dphy_clk_lane_cfg cfg);
+	void (*set_pll_cfg)(struct cdns_dphy *dphy,
+			    const struct cdns_dphy_cfg *cfg);
+	unsigned long (*get_wakeup_time_ns)(struct cdns_dphy *dphy);
+};
+
+struct cdns_dphy {
+	struct cdns_dphy_cfg cfg;
+	void __iomem *regs;
+	struct clk *psm_clk;
+	struct clk *pll_ref_clk;
+	const struct cdns_dphy_ops *ops;
+	struct phy *phy;
+};
+
+static int cdns_dsi_get_dphy_pll_cfg(struct cdns_dphy *dphy,
+				     struct cdns_dphy_cfg *cfg,
+				     struct phy_configure_opts_mipi_dphy *opts,
+				     unsigned int *dsi_hfp_ext)
+{
+	unsigned long pll_ref_hz = clk_get_rate(dphy->pll_ref_clk);
+	u64 dlane_bps;
+
+	memset(cfg, 0, sizeof(*cfg));
+
+	if (pll_ref_hz < 9600000 || pll_ref_hz >= 150000000)
+		return -EINVAL;
+	else if (pll_ref_hz < 19200000)
+		cfg->pll_ipdiv = 1;
+	else if (pll_ref_hz < 38400000)
+		cfg->pll_ipdiv = 2;
+	else if (pll_ref_hz < 76800000)
+		cfg->pll_ipdiv = 4;
+	else
+		cfg->pll_ipdiv = 8;
+
+	dlane_bps = opts->hs_clk_rate;
+
+	if (dlane_bps > 2500000000UL || dlane_bps < 160000000UL)
+		return -EINVAL;
+	else if (dlane_bps >= 1250000000)
+		cfg->pll_opdiv = 1;
+	else if (dlane_bps >= 630000000)
+		cfg->pll_opdiv = 2;
+	else if (dlane_bps >= 320000000)
+		cfg->pll_opdiv = 4;
+	else if (dlane_bps >= 160000000)
+		cfg->pll_opdiv = 8;
+
+	cfg->pll_fbdiv = DIV_ROUND_UP_ULL(dlane_bps * 2 * cfg->pll_opdiv *
+					  cfg->pll_ipdiv,
+					  pll_ref_hz);
+
+	return 0;
+}
+
+static int cdns_dphy_setup_psm(struct cdns_dphy *dphy)
+{
+	unsigned long psm_clk_hz = clk_get_rate(dphy->psm_clk);
+	unsigned long psm_div;
+
+	if (!psm_clk_hz || psm_clk_hz > 100000000)
+		return -EINVAL;
+
+	psm_div = DIV_ROUND_CLOSEST(psm_clk_hz, 1000000);
+	if (dphy->ops->set_psm_div)
+		dphy->ops->set_psm_div(dphy, psm_div);
+
+	return 0;
+}
+
+static void cdns_dphy_set_clk_lane_cfg(struct cdns_dphy *dphy,
+				       enum cdns_dphy_clk_lane_cfg cfg)
+{
+	if (dphy->ops->set_clk_lane_cfg)
+		dphy->ops->set_clk_lane_cfg(dphy, cfg);
+}
+
+static void cdns_dphy_set_pll_cfg(struct cdns_dphy *dphy,
+				  const struct cdns_dphy_cfg *cfg)
+{
+	if (dphy->ops->set_pll_cfg)
+		dphy->ops->set_pll_cfg(dphy, cfg);
+}
+
+static unsigned long cdns_dphy_get_wakeup_time_ns(struct cdns_dphy *dphy)
+{
+	return dphy->ops->get_wakeup_time_ns(dphy);
+}
+
+static unsigned long cdns_dphy_ref_get_wakeup_time_ns(struct cdns_dphy *dphy)
+{
+	/* Default wakeup time is 800 ns (in a simulated environment). */
+	return 800;
+}
+
+static void cdns_dphy_ref_set_pll_cfg(struct cdns_dphy *dphy,
+				      const struct cdns_dphy_cfg *cfg)
+{
+	u32 fbdiv_low, fbdiv_high;
+
+	fbdiv_low = (cfg->pll_fbdiv / 4) - 2;
+	fbdiv_high = cfg->pll_fbdiv - fbdiv_low - 2;
+
+	writel(DPHY_CMN_IPDIV_FROM_REG | DPHY_CMN_OPDIV_FROM_REG |
+	       DPHY_CMN_IPDIV(cfg->pll_ipdiv) |
+	       DPHY_CMN_OPDIV(cfg->pll_opdiv),
+	       dphy->regs + DPHY_CMN_OPIPDIV);
+	writel(DPHY_CMN_FBDIV_FROM_REG |
+	       DPHY_CMN_FBDIV_VAL(fbdiv_low, fbdiv_high),
+	       dphy->regs + DPHY_CMN_FBDIV);
+	writel(DPHY_CMN_PWM_HIGH(6) | DPHY_CMN_PWM_LOW(0x101) |
+	       DPHY_CMN_PWM_DIV(0x8),
+	       dphy->regs + DPHY_CMN_PWM);
+}
+
+static void cdns_dphy_ref_set_psm_div(struct cdns_dphy *dphy, u8 div)
+{
+	writel(DPHY_PSM_CFG_FROM_REG | DPHY_PSM_CLK_DIV(div),
+	       dphy->regs + DPHY_PSM_CFG);
+}
+
+/*
+ * This is the reference implementation of DPHY hooks. Specific integration of
+ * this IP may have to re-implement some of them depending on how they decided
+ * to wire things in the SoC.
+ */
+static const struct cdns_dphy_ops ref_dphy_ops = {
+	.get_wakeup_time_ns = cdns_dphy_ref_get_wakeup_time_ns,
+	.set_pll_cfg = cdns_dphy_ref_set_pll_cfg,
+	.set_psm_div = cdns_dphy_ref_set_psm_div,
+};
+
+static int cdns_dphy_config_from_opts(struct phy *phy,
+				      struct phy_configure_opts_mipi_dphy *opts,
+				      struct cdns_dphy_cfg *cfg)
+{
+	struct cdns_dphy *dphy = phy_get_drvdata(phy);
+	unsigned int dsi_hfp_ext = 0;
+	int ret;
+
+	ret = phy_mipi_dphy_config_validate(opts);
+	if (ret)
+		return ret;
+
+	ret = cdns_dsi_get_dphy_pll_cfg(dphy, cfg,
+					opts, &dsi_hfp_ext);
+	if (ret)
+		return ret;
+
+	opts->wakeup = cdns_dphy_get_wakeup_time_ns(dphy) / 1000;
+
+	return 0;
+}
+
+static int cdns_dphy_validate(struct phy *phy, enum phy_mode mode, int submode,
+			      union phy_configure_opts *opts)
+{
+	struct cdns_dphy_cfg cfg = { 0 };
+
+	if (mode != PHY_MODE_MIPI_DPHY)
+		return -EINVAL;
+
+	return cdns_dphy_config_from_opts(phy, &opts->mipi_dphy, &cfg);
+}
+
+static int cdns_dphy_configure(struct phy *phy, union phy_configure_opts *opts)
+{
+	struct cdns_dphy *dphy = phy_get_drvdata(phy);
+	struct cdns_dphy_cfg cfg = { 0 };
+	int ret;
+
+	ret = cdns_dphy_config_from_opts(phy, &opts->mipi_dphy, &cfg);
+	if (ret)
+		return ret;
+
+	/*
+	 * Configure the internal PSM clk divider so that the DPHY has a
+	 * 1MHz clk (or something close).
+	 */
+	ret = cdns_dphy_setup_psm(dphy);
+	if (ret)
+		return ret;
+
+	/*
+	 * Configure attach clk lanes to data lanes: the DPHY has 2 clk lanes
+	 * and 8 data lanes, each clk lane can be attache different set of
+	 * data lanes. The 2 groups are named 'left' and 'right', so here we
+	 * just say that we want the 'left' clk lane to drive the 'left' data
+	 * lanes.
+	 */
+	cdns_dphy_set_clk_lane_cfg(dphy, DPHY_CLK_CFG_LEFT_DRIVES_LEFT);
+
+	/*
+	 * Configure the DPHY PLL that will be used to generate the TX byte
+	 * clk.
+	 */
+	cdns_dphy_set_pll_cfg(dphy, &cfg);
+
+	return 0;
+}
+
+static int cdns_dphy_power_on(struct phy *phy)
+{
+	struct cdns_dphy *dphy = phy_get_drvdata(phy);
+
+	clk_prepare_enable(dphy->psm_clk);
+	clk_prepare_enable(dphy->pll_ref_clk);
+
+	/* Start TX state machine. */
+	writel(DPHY_CMN_SSM_EN | DPHY_CMN_TX_MODE_EN,
+	       dphy->regs + DPHY_CMN_SSM);
+
+	return 0;
+}
+
+static int cdns_dphy_power_off(struct phy *phy)
+{
+	struct cdns_dphy *dphy = phy_get_drvdata(phy);
+
+	clk_disable_unprepare(dphy->pll_ref_clk);
+	clk_disable_unprepare(dphy->psm_clk);
+
+	return 0;
+}
+
+static const struct phy_ops cdns_dphy_ops = {
+	.configure	= cdns_dphy_configure,
+	.validate	= cdns_dphy_validate,
+	.power_on	= cdns_dphy_power_on,
+	.power_off	= cdns_dphy_power_off,
+};
+
+static int cdns_dphy_probe(struct platform_device *pdev)
+{
+	struct phy_provider *phy_provider;
+	struct cdns_dphy *dphy;
+	struct resource *res;
+	int ret;
+
+	dphy = devm_kzalloc(&pdev->dev, sizeof(*dphy), GFP_KERNEL);
+	if (!dphy)
+		return -ENOMEM;
+	dev_set_drvdata(&pdev->dev, dphy);
+
+	dphy->ops = of_device_get_match_data(&pdev->dev);
+	if (!dphy->ops)
+		return -EINVAL;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	dphy->regs = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(dphy->regs))
+		return PTR_ERR(dphy->regs);
+
+	dphy->psm_clk = devm_clk_get(&pdev->dev, "psm");
+	if (IS_ERR(dphy->psm_clk))
+		return PTR_ERR(dphy->psm_clk);
+
+	dphy->pll_ref_clk = devm_clk_get(&pdev->dev, "pll_ref");
+	if (IS_ERR(dphy->pll_ref_clk))
+		return PTR_ERR(dphy->pll_ref_clk);
+
+	if (dphy->ops->probe) {
+		ret = dphy->ops->probe(dphy);
+		if (ret)
+			return ret;
+	}
+
+	dphy->phy = devm_phy_create(&pdev->dev, NULL, &cdns_dphy_ops);
+	if (IS_ERR(dphy->phy)) {
+		dev_err(&pdev->dev, "failed to create PHY\n");
+		if (dphy->ops->remove)
+			dphy->ops->remove(dphy);
+		return PTR_ERR(dphy->phy);
+	}
+
+	phy_set_drvdata(dphy->phy, dphy);
+	phy_provider = devm_of_phy_provider_register(&pdev->dev,
+						     of_phy_simple_xlate);
+
+	return PTR_ERR_OR_ZERO(phy_provider);
+}
+
+static int cdns_dphy_remove(struct platform_device *pdev)
+{
+	struct cdns_dphy *dphy = dev_get_drvdata(&pdev->dev);
+
+	if (dphy->ops->remove)
+		dphy->ops->remove(dphy);
+
+	return 0;
+}
+
+static const struct of_device_id cdns_dphy_of_match[] = {
+	{ .compatible = "cdns,dphy", .data = &ref_dphy_ops },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, cdns_dphy_of_match);
+
+static struct platform_driver cdns_dphy_platform_driver = {
+	.probe		= cdns_dphy_probe,
+	.remove		= cdns_dphy_remove,
+	.driver		= {
+		.name		= "cdns-mipi-dphy",
+		.of_match_table	= cdns_dphy_of_match,
+	},
+};
+module_platform_driver(cdns_dphy_platform_driver);
+
+MODULE_AUTHOR("Maxime Ripard <maxime.ripard@bootlin.com>");
+MODULE_DESCRIPTION("Cadence MIPI D-PHY Driver");
+MODULE_LICENSE("GPL");