phy: Add driver for mixel mipi dphy found on NXP's i.MX8 SoCs

This adds support for the Mixel DPHY as found on i.MX8 CPUs but since
this is an IP core it will likely be found on others in the future. So
instead of adding this to the nwl host driver make it a generic PHY
driver.

The driver supports the i.MX8MQ. Support for i.MX8QM and i.MX8QXP can be
added once the necessary system controller bits are in via
mixel_dphy_devdata.

Signed-off-by: Guido Günther <agx@sigxcpu.org>
Co-developed-by: Robert Chiras <robert.chiras@nxp.com>
Signed-off-by: Robert Chiras <robert.chiras@nxp.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

3 files changed, 508 insertions, 0 deletions

diff --git a/drivers/phy/freescale/Kconfig b/drivers/phy/freescale/Kconfig
index 832670b4952b..247be62d0981 100644
--- a/drivers/phy/freescale/Kconfig
+++ b/drivers/phy/freescale/Kconfig
@@ -3,3 +3,13 @@ config PHY_FSL_IMX8MQ_USB
 	depends on OF && HAS_IOMEM
 	select GENERIC_PHY
 	default ARCH_MXC && ARM64
+
+config PHY_MIXEL_MIPI_DPHY
+	tristate "Mixel MIPI DSI PHY support"
+	depends on OF && HAS_IOMEM
+	select GENERIC_PHY
+	select GENERIC_PHY_MIPI_DPHY
+	select REGMAP_MMIO
+	help
+	  Enable this to add support for the Mixel DSI PHY as found
+	  on NXP's i.MX8 family of SOCs.
diff --git a/drivers/phy/freescale/Makefile b/drivers/phy/freescale/Makefile
index dc2b3f1f2f80..07491c926a2c 100644
--- a/drivers/phy/freescale/Makefile
+++ b/drivers/phy/freescale/Makefile
@@ -1 +1,2 @@
 obj-$(CONFIG_PHY_FSL_IMX8MQ_USB)	+= phy-fsl-imx8mq-usb.o
+obj-$(CONFIG_PHY_MIXEL_MIPI_DPHY)	+= phy-fsl-imx8-mipi-dphy.o
diff --git a/drivers/phy/freescale/phy-fsl-imx8-mipi-dphy.c b/drivers/phy/freescale/phy-fsl-imx8-mipi-dphy.c
new file mode 100644
index 000000000000..9f2c1da14f5a
--- /dev/null
+++ b/drivers/phy/freescale/phy-fsl-imx8-mipi-dphy.c
@@ -0,0 +1,497 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2017,2018 NXP
+ * Copyright 2019 Purism SPC
+ */
+
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/phy/phy.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+/* DPHY registers */
+#define DPHY_PD_DPHY			0x00
+#define DPHY_M_PRG_HS_PREPARE		0x04
+#define DPHY_MC_PRG_HS_PREPARE		0x08
+#define DPHY_M_PRG_HS_ZERO		0x0c
+#define DPHY_MC_PRG_HS_ZERO		0x10
+#define DPHY_M_PRG_HS_TRAIL		0x14
+#define DPHY_MC_PRG_HS_TRAIL		0x18
+#define DPHY_PD_PLL			0x1c
+#define DPHY_TST			0x20
+#define DPHY_CN				0x24
+#define DPHY_CM				0x28
+#define DPHY_CO				0x2c
+#define DPHY_LOCK			0x30
+#define DPHY_LOCK_BYP			0x34
+#define DPHY_REG_BYPASS_PLL		0x4C
+
+#define MBPS(x) ((x) * 1000000)
+
+#define DATA_RATE_MAX_SPEED MBPS(1500)
+#define DATA_RATE_MIN_SPEED MBPS(80)
+
+#define PLL_LOCK_SLEEP 10
+#define PLL_LOCK_TIMEOUT 1000
+
+#define CN_BUF	0xcb7a89c0
+#define CO_BUF	0x63
+#define CM(x)	(				  \
+		((x) <	32) ? 0xe0 | ((x) - 16) : \
+		((x) <	64) ? 0xc0 | ((x) - 32) : \
+		((x) < 128) ? 0x80 | ((x) - 64) : \
+		((x) - 128))
+#define CN(x)	(((x) == 1) ? 0x1f : (((CN_BUF) >> ((x) - 1)) & 0x1f))
+#define CO(x)	((CO_BUF) >> (8 - (x)) & 0x03)
+
+/* PHY power on is active low */
+#define PWR_ON	0
+#define PWR_OFF	1
+
+enum mixel_dphy_devtype {
+	MIXEL_IMX8MQ,
+};
+
+struct mixel_dphy_devdata {
+	u8 reg_tx_rcal;
+	u8 reg_auto_pd_en;
+	u8 reg_rxlprp;
+	u8 reg_rxcdrp;
+	u8 reg_rxhs_settle;
+};
+
+static const struct mixel_dphy_devdata mixel_dphy_devdata[] = {
+	[MIXEL_IMX8MQ] = {
+		.reg_tx_rcal = 0x38,
+		.reg_auto_pd_en = 0x3c,
+		.reg_rxlprp = 0x40,
+		.reg_rxcdrp = 0x44,
+		.reg_rxhs_settle = 0x48,
+	},
+};
+
+struct mixel_dphy_cfg {
+	/* DPHY PLL parameters */
+	u32 cm;
+	u32 cn;
+	u32 co;
+	/* DPHY register values */
+	u8 mc_prg_hs_prepare;
+	u8 m_prg_hs_prepare;
+	u8 mc_prg_hs_zero;
+	u8 m_prg_hs_zero;
+	u8 mc_prg_hs_trail;
+	u8 m_prg_hs_trail;
+	u8 rxhs_settle;
+};
+
+struct mixel_dphy_priv {
+	struct mixel_dphy_cfg cfg;
+	struct regmap *regmap;
+	struct clk *phy_ref_clk;
+	const struct mixel_dphy_devdata *devdata;
+};
+
+static const struct regmap_config mixel_dphy_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 32,
+	.reg_stride = 4,
+	.max_register = DPHY_REG_BYPASS_PLL,
+	.name = "mipi-dphy",
+};
+
+static int phy_write(struct phy *phy, u32 value, unsigned int reg)
+{
+	struct mixel_dphy_priv *priv = phy_get_drvdata(phy);
+	int ret;
+
+	ret = regmap_write(priv->regmap, reg, value);
+	if (ret < 0)
+		dev_err(&phy->dev, "Failed to write DPHY reg %d: %d\n", reg,
+			ret);
+	return ret;
+}
+
+/*
+ * Find a ratio close to the desired one using continued fraction
+ * approximation ending either at exact match or maximum allowed
+ * nominator, denominator.
+ */
+static void get_best_ratio(u32 *pnum, u32 *pdenom, u32 max_n, u32 max_d)
+{
+	u32 a = *pnum;
+	u32 b = *pdenom;
+	u32 c;
+	u32 n[] = {0, 1};
+	u32 d[] = {1, 0};
+	u32 whole;
+	unsigned int i = 1;
+
+	while (b) {
+		i ^= 1;
+		whole = a / b;
+		n[i] += (n[i ^ 1] * whole);
+		d[i] += (d[i ^ 1] * whole);
+		if ((n[i] > max_n) || (d[i] > max_d)) {
+			i ^= 1;
+			break;
+		}
+		c = a - (b * whole);
+		a = b;
+		b = c;
+	}
+	*pnum = n[i];
+	*pdenom = d[i];
+}
+
+static int mixel_dphy_config_from_opts(struct phy *phy,
+	       struct phy_configure_opts_mipi_dphy *dphy_opts,
+	       struct mixel_dphy_cfg *cfg)
+{
+	struct mixel_dphy_priv *priv = dev_get_drvdata(phy->dev.parent);
+	unsigned long ref_clk = clk_get_rate(priv->phy_ref_clk);
+	u32 lp_t, numerator, denominator;
+	unsigned long long tmp;
+	u32 n;
+	int i;
+
+	if (dphy_opts->hs_clk_rate > DATA_RATE_MAX_SPEED ||
+	    dphy_opts->hs_clk_rate < DATA_RATE_MIN_SPEED)
+		return -EINVAL;
+
+	numerator = dphy_opts->hs_clk_rate;
+	denominator = ref_clk;
+	get_best_ratio(&numerator, &denominator, 255, 256);
+	if (!numerator || !denominator) {
+		dev_err(&phy->dev, "Invalid %d/%d for %ld/%ld\n",
+			numerator, denominator,
+			dphy_opts->hs_clk_rate, ref_clk);
+		return -EINVAL;
+	}
+
+	while ((numerator < 16) && (denominator <= 128)) {
+		numerator <<= 1;
+		denominator <<= 1;
+	}
+	/*
+	 * CM ranges between 16 and 255
+	 * CN ranges between 1 and 32
+	 * CO is power of 2: 1, 2, 4, 8
+	 */
+	i = __ffs(denominator);
+	if (i > 3)
+		i = 3;
+	cfg->cn = denominator >> i;
+	cfg->co = 1 << i;
+	cfg->cm = numerator;
+
+	if (cfg->cm < 16 || cfg->cm > 255 ||
+	    cfg->cn < 1 || cfg->cn > 32 ||
+	    cfg->co < 1 || cfg->co > 8) {
+		dev_err(&phy->dev, "Invalid CM/CN/CO values: %u/%u/%u\n",
+			cfg->cm, cfg->cn, cfg->co);
+		dev_err(&phy->dev, "for hs_clk/ref_clk=%ld/%ld ~ %d/%d\n",
+			dphy_opts->hs_clk_rate, ref_clk,
+			numerator, denominator);
+		return -EINVAL;
+	}
+
+	dev_dbg(&phy->dev, "hs_clk/ref_clk=%ld/%ld ~ %d/%d\n",
+		dphy_opts->hs_clk_rate, ref_clk, numerator, denominator);
+
+	/* LP clock period */
+	tmp = 1000000000000LL;
+	do_div(tmp, dphy_opts->lp_clk_rate); /* ps */
+	if (tmp > ULONG_MAX)
+		return -EINVAL;
+
+	lp_t = tmp;
+	dev_dbg(&phy->dev, "LP clock %lu, period: %u ps\n",
+		dphy_opts->lp_clk_rate, lp_t);
+
+	/* hs_prepare: in lp clock periods */
+	if (2 * dphy_opts->hs_prepare > 5 * lp_t) {
+		dev_err(&phy->dev,
+			"hs_prepare (%u) > 2.5 * lp clock period (%u)\n",
+			dphy_opts->hs_prepare, lp_t);
+		return -EINVAL;
+	}
+	/* 00: lp_t, 01: 1.5 * lp_t, 10: 2 * lp_t, 11: 2.5 * lp_t */
+	if (dphy_opts->hs_prepare < lp_t) {
+		n = 0;
+	} else {
+		tmp = 2 * (dphy_opts->hs_prepare - lp_t);
+		do_div(tmp, lp_t);
+		n = tmp;
+	}
+	cfg->m_prg_hs_prepare = n;
+
+	/* clk_prepare: in lp clock periods */
+	if (2 * dphy_opts->clk_prepare > 3 * lp_t) {
+		dev_err(&phy->dev,
+			"clk_prepare (%u) > 1.5 * lp clock period (%u)\n",
+			dphy_opts->clk_prepare, lp_t);
+		return -EINVAL;
+	}
+	/* 00: lp_t, 01: 1.5 * lp_t */
+	cfg->mc_prg_hs_prepare = dphy_opts->clk_prepare > lp_t ? 1 : 0;
+
+	/* hs_zero: formula from NXP BSP */
+	n = (144 * (dphy_opts->hs_clk_rate / 1000000) - 47500) / 10000;
+	cfg->m_prg_hs_zero = n < 1 ? 1 : n;
+
+	/* clk_zero: formula from NXP BSP */
+	n = (34 * (dphy_opts->hs_clk_rate / 1000000) - 2500) / 1000;
+	cfg->mc_prg_hs_zero = n < 1 ? 1 : n;
+
+	/* clk_trail, hs_trail: formula from NXP BSP */
+	n = (103 * (dphy_opts->hs_clk_rate / 1000000) + 10000) / 10000;
+	if (n > 15)
+		n = 15;
+	if (n < 1)
+		n = 1;
+	cfg->m_prg_hs_trail = n;
+	cfg->mc_prg_hs_trail = n;
+
+	/* rxhs_settle: formula from NXP BSP */
+	if (dphy_opts->hs_clk_rate < MBPS(80))
+		cfg->rxhs_settle = 0x0d;
+	else if (dphy_opts->hs_clk_rate < MBPS(90))
+		cfg->rxhs_settle = 0x0c;
+	else if (dphy_opts->hs_clk_rate < MBPS(125))
+		cfg->rxhs_settle = 0x0b;
+	else if (dphy_opts->hs_clk_rate < MBPS(150))
+		cfg->rxhs_settle = 0x0a;
+	else if (dphy_opts->hs_clk_rate < MBPS(225))
+		cfg->rxhs_settle = 0x09;
+	else if (dphy_opts->hs_clk_rate < MBPS(500))
+		cfg->rxhs_settle = 0x08;
+	else
+		cfg->rxhs_settle = 0x07;
+
+	dev_dbg(&phy->dev, "phy_config: %u %u %u %u %u %u %u\n",
+		cfg->m_prg_hs_prepare, cfg->mc_prg_hs_prepare,
+		cfg->m_prg_hs_zero, cfg->mc_prg_hs_zero,
+		cfg->m_prg_hs_trail, cfg->mc_prg_hs_trail,
+		cfg->rxhs_settle);
+
+	return 0;
+}
+
+static void mixel_phy_set_hs_timings(struct phy *phy)
+{
+	struct mixel_dphy_priv *priv = phy_get_drvdata(phy);
+
+	phy_write(phy, priv->cfg.m_prg_hs_prepare, DPHY_M_PRG_HS_PREPARE);
+	phy_write(phy, priv->cfg.mc_prg_hs_prepare, DPHY_MC_PRG_HS_PREPARE);
+	phy_write(phy, priv->cfg.m_prg_hs_zero, DPHY_M_PRG_HS_ZERO);
+	phy_write(phy, priv->cfg.mc_prg_hs_zero, DPHY_MC_PRG_HS_ZERO);
+	phy_write(phy, priv->cfg.m_prg_hs_trail, DPHY_M_PRG_HS_TRAIL);
+	phy_write(phy, priv->cfg.mc_prg_hs_trail, DPHY_MC_PRG_HS_TRAIL);
+	phy_write(phy, priv->cfg.rxhs_settle, priv->devdata->reg_rxhs_settle);
+}
+
+static int mixel_dphy_set_pll_params(struct phy *phy)
+{
+	struct mixel_dphy_priv *priv = dev_get_drvdata(phy->dev.parent);
+
+	if (priv->cfg.cm < 16 || priv->cfg.cm > 255 ||
+	    priv->cfg.cn < 1 || priv->cfg.cn > 32 ||
+	    priv->cfg.co < 1 || priv->cfg.co > 8) {
+		dev_err(&phy->dev, "Invalid CM/CN/CO values! (%u/%u/%u)\n",
+			priv->cfg.cm, priv->cfg.cn, priv->cfg.co);
+		return -EINVAL;
+	}
+	dev_dbg(&phy->dev, "Using CM:%u CN:%u CO:%u\n",
+		priv->cfg.cm, priv->cfg.cn, priv->cfg.co);
+	phy_write(phy, CM(priv->cfg.cm), DPHY_CM);
+	phy_write(phy, CN(priv->cfg.cn), DPHY_CN);
+	phy_write(phy, CO(priv->cfg.co), DPHY_CO);
+	return 0;
+}
+
+static int mixel_dphy_configure(struct phy *phy, union phy_configure_opts *opts)
+{
+	struct mixel_dphy_priv *priv = phy_get_drvdata(phy);
+	struct mixel_dphy_cfg cfg = { 0 };
+	int ret;
+
+	ret = mixel_dphy_config_from_opts(phy, &opts->mipi_dphy, &cfg);
+	if (ret)
+		return ret;
+
+	/* Update the configuration */
+	memcpy(&priv->cfg, &cfg, sizeof(struct mixel_dphy_cfg));
+
+	phy_write(phy, 0x00, DPHY_LOCK_BYP);
+	phy_write(phy, 0x01, priv->devdata->reg_tx_rcal);
+	phy_write(phy, 0x00, priv->devdata->reg_auto_pd_en);
+	phy_write(phy, 0x02, priv->devdata->reg_rxlprp);
+	phy_write(phy, 0x02, priv->devdata->reg_rxcdrp);
+	phy_write(phy, 0x25, DPHY_TST);
+
+	mixel_phy_set_hs_timings(phy);
+	ret = mixel_dphy_set_pll_params(phy);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+static int mixel_dphy_validate(struct phy *phy, enum phy_mode mode, int submode,
+			       union phy_configure_opts *opts)
+{
+	struct mixel_dphy_cfg cfg = { 0 };
+
+	if (mode != PHY_MODE_MIPI_DPHY)
+		return -EINVAL;
+
+	return mixel_dphy_config_from_opts(phy, &opts->mipi_dphy, &cfg);
+}
+
+static int mixel_dphy_init(struct phy *phy)
+{
+	phy_write(phy, PWR_OFF, DPHY_PD_PLL);
+	phy_write(phy, PWR_OFF, DPHY_PD_DPHY);
+
+	return 0;
+}
+
+static int mixel_dphy_exit(struct phy *phy)
+{
+	phy_write(phy, 0, DPHY_CM);
+	phy_write(phy, 0, DPHY_CN);
+	phy_write(phy, 0, DPHY_CO);
+
+	return 0;
+}
+
+static int mixel_dphy_power_on(struct phy *phy)
+{
+	struct mixel_dphy_priv *priv = phy_get_drvdata(phy);
+	u32 locked;
+	int ret;
+
+	ret = clk_prepare_enable(priv->phy_ref_clk);
+	if (ret < 0)
+		return ret;
+
+	phy_write(phy, PWR_ON, DPHY_PD_PLL);
+	ret = regmap_read_poll_timeout(priv->regmap, DPHY_LOCK, locked,
+				       locked, PLL_LOCK_SLEEP,
+				       PLL_LOCK_TIMEOUT);
+	if (ret < 0) {
+		dev_err(&phy->dev, "Could not get DPHY lock (%d)!\n", ret);
+		goto clock_disable;
+	}
+	phy_write(phy, PWR_ON, DPHY_PD_DPHY);
+
+	return 0;
+clock_disable:
+	clk_disable_unprepare(priv->phy_ref_clk);
+	return ret;
+}
+
+static int mixel_dphy_power_off(struct phy *phy)
+{
+	struct mixel_dphy_priv *priv = phy_get_drvdata(phy);
+
+	phy_write(phy, PWR_OFF, DPHY_PD_PLL);
+	phy_write(phy, PWR_OFF, DPHY_PD_DPHY);
+
+	clk_disable_unprepare(priv->phy_ref_clk);
+
+	return 0;
+}
+
+static const struct phy_ops mixel_dphy_phy_ops = {
+	.init = mixel_dphy_init,
+	.exit = mixel_dphy_exit,
+	.power_on = mixel_dphy_power_on,
+	.power_off = mixel_dphy_power_off,
+	.configure = mixel_dphy_configure,
+	.validate = mixel_dphy_validate,
+	.owner = THIS_MODULE,
+};
+
+static const struct of_device_id mixel_dphy_of_match[] = {
+	{ .compatible = "fsl,imx8mq-mipi-dphy",
+	  .data = &mixel_dphy_devdata[MIXEL_IMX8MQ] },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, mixel_dphy_of_match);
+
+static int mixel_dphy_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+	struct phy_provider *phy_provider;
+	struct mixel_dphy_priv *priv;
+	struct resource *res;
+	struct phy *phy;
+	void __iomem *base;
+
+	if (!np)
+		return -ENODEV;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->devdata = of_device_get_match_data(&pdev->dev);
+	if (!priv->devdata)
+		return -EINVAL;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	priv->regmap = devm_regmap_init_mmio(&pdev->dev, base,
+					     &mixel_dphy_regmap_config);
+	if (IS_ERR(priv->regmap)) {
+		dev_err(dev, "Couldn't create the DPHY regmap\n");
+		return PTR_ERR(priv->regmap);
+	}
+
+	priv->phy_ref_clk = devm_clk_get(&pdev->dev, "phy_ref");
+	if (IS_ERR(priv->phy_ref_clk)) {
+		dev_err(dev, "No phy_ref clock found\n");
+		return PTR_ERR(priv->phy_ref_clk);
+	}
+	dev_dbg(dev, "phy_ref clock rate: %lu\n",
+		clk_get_rate(priv->phy_ref_clk));
+
+	dev_set_drvdata(dev, priv);
+
+	phy = devm_phy_create(dev, np, &mixel_dphy_phy_ops);
+	if (IS_ERR(phy)) {
+		dev_err(dev, "Failed to create phy %ld\n", PTR_ERR(phy));
+		return PTR_ERR(phy);
+	}
+	phy_set_drvdata(phy, priv);
+
+	phy_provider = devm_of_phy_provider_register(dev, of_phy_simple_xlate);
+
+	return PTR_ERR_OR_ZERO(phy_provider);
+}
+
+static struct platform_driver mixel_dphy_driver = {
+	.probe	= mixel_dphy_probe,
+	.driver = {
+		.name = "mixel-mipi-dphy",
+		.of_match_table	= mixel_dphy_of_match,
+	}
+};
+module_platform_driver(mixel_dphy_driver);
+
+MODULE_AUTHOR("NXP Semiconductor");
+MODULE_DESCRIPTION("Mixel MIPI-DSI PHY driver");
+MODULE_LICENSE("GPL");