[LINUX PATCH 3/3] pwm: pwm-cadence: Add support for TTC PWM

[Mubin Sayyed]

Cadence TTC timer can be configured as clocksource/clockevent
or PWM device. Specific TTC device would be configured as PWM
device, if pwm-cells property is present in the device tree
node.

In case of Zynq, ZynqMP and Versal SoC's, each TTC device has 3
timers/counters, so maximum 3 PWM channels can be configured for
each TTC IP instance. Also, output of 0th PWM channel of each TTC
device can be routed to MIO or EMIO, and output of 2nd and 3rd
PWM channel can be routed only to EMIO.

Period for given PWM channel is configured through interval timer
and duty cycle through match counter.

Signed-off-by: Mubin Sayyed <mubin.sayyed@xxxxxxx>
---
 drivers/pwm/Kconfig       |  11 ++
 drivers/pwm/Makefile      |   1 +
 drivers/pwm/pwm-cadence.c | 363 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 375 insertions(+)
 create mode 100644 drivers/pwm/pwm-cadence.c

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index dae023d783a2..9e0f1fae4711 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -504,6 +504,17 @@ config PWM_SIFIVE
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-sifive.
 
+config PWM_CADENCE
+	tristate "Cadence PWM support"
+	depends on OF
+	depends on COMMON_CLK
+	help
+	  Generic PWM framework driver for cadence TTC IP found on
+	  Xilinx Zynq/ZynqMP/Versal SOCs. Each TTC device has 3 PWM
+	  channels. Output of 0th PWM channel of each TTC device can
+	  be routed to MIO or EMIO, and output of 1st and 2nd PWM
+	  channels can be routed only to EMIO.
+
 config PWM_SL28CPLD
 	tristate "Kontron sl28cpld PWM support"
 	depends on MFD_SL28CPLD || COMPILE_TEST
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index 7bf1a29f02b8..f744f021be0f 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -46,6 +46,7 @@ obj-$(CONFIG_PWM_RENESAS_TPU)	+= pwm-renesas-tpu.o
 obj-$(CONFIG_PWM_ROCKCHIP)	+= pwm-rockchip.o
 obj-$(CONFIG_PWM_SAMSUNG)	+= pwm-samsung.o
 obj-$(CONFIG_PWM_SIFIVE)	+= pwm-sifive.o
+obj-$(CONFIG_PWM_CADENCE)	+= pwm-cadence.o
 obj-$(CONFIG_PWM_SL28CPLD)	+= pwm-sl28cpld.o
 obj-$(CONFIG_PWM_SPEAR)		+= pwm-spear.o
 obj-$(CONFIG_PWM_SPRD)		+= pwm-sprd.o
diff --git a/drivers/pwm/pwm-cadence.c b/drivers/pwm/pwm-cadence.c
new file mode 100644
index 000000000000..de981df3ec5a
--- /dev/null
+++ b/drivers/pwm/pwm-cadence.c
@@ -0,0 +1,363 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver to configure cadence TTC timer as PWM
+ * generator
+ *
+ * Copyright (C) 2022, Advanced Micro Devices, Inc.
+ */
+
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/of_address.h>
+
+#define TTC_CLK_CNTRL_OFFSET		0x00
+#define TTC_CNT_CNTRL_OFFSET		0x0C
+#define TTC_MATCH_CNT_VAL_OFFSET	0x30
+#define TTC_COUNT_VAL_OFFSET		0x18
+#define TTC_INTR_VAL_OFFSET		0x24
+#define TTC_ISR_OFFSET			0x54
+#define TTC_IER_OFFSET			0x60
+#define TTC_PWM_CHANNEL_OFFSET		0x4
+
+#define TTC_CLK_CNTRL_CSRC_MASK		BIT(5)
+#define TTC_CLK_CNTRL_PSV_MASK		GENMASK(4, 1)
+
+#define TTC_CNTR_CTRL_DIS_MASK		BIT(0)
+#define TTC_CNTR_CTRL_INTR_MODE_EN_MASK	BIT(1)
+#define TTC_CNTR_CTRL_MATCH_MODE_EN_MASK	BIT(3)
+#define TTC_CNTR_CTRL_RST_MASK		BIT(4)
+#define TTC_CNTR_CTRL_WAVE_EN_MASK	BIT(5)
+#define TTC_CNTR_CTRL_WAVE_POL_MASK	BIT(6)
+
+#define TTC_CLK_CNTRL_PSV_SHIFT		1
+
+#define TTC_PWM_MAX_CH			3
+
+/**
+ * struct ttc_pwm_priv - Private data for TTC PWM drivers
+ * @chip:	PWM chip structure representing PWM controller
+ * @clk:	TTC input clock
+ * @max:	Maximum value of the counters
+ * @base:	Base address of TTC instance
+ */
+struct ttc_pwm_priv {
+	struct pwm_chip chip;
+	struct clk *clk;
+	u32 max;
+	void __iomem *base;
+};
+
+static inline u32 ttc_pwm_readl(struct ttc_pwm_priv *priv,
+				unsigned long offset)
+{
+	return readl_relaxed(priv->base + offset);
+}
+
+static inline void ttc_pwm_writel(struct ttc_pwm_priv *priv,
+				  unsigned long offset,
+				  unsigned long val)
+{
+	writel_relaxed(val, priv->base + offset);
+}
+
+static inline u32 ttc_pwm_ch_readl(struct ttc_pwm_priv *priv,
+				   struct pwm_device *pwm,
+				   unsigned long offset)
+{
+	unsigned long pwm_ch_offset = offset +
+				       (TTC_PWM_CHANNEL_OFFSET * pwm->hwpwm);
+
+	return ttc_pwm_readl(priv, pwm_ch_offset);
+}
+
+static inline void ttc_pwm_ch_writel(struct ttc_pwm_priv *priv,
+				     struct pwm_device *pwm,
+				     unsigned long offset,
+				     unsigned long val)
+{
+	unsigned long pwm_ch_offset = offset +
+				       (TTC_PWM_CHANNEL_OFFSET * pwm->hwpwm);
+
+	ttc_pwm_writel(priv, pwm_ch_offset, val);
+}
+
+static inline struct ttc_pwm_priv *xilinx_pwm_chip_to_priv(struct pwm_chip *chip)
+{
+	return container_of(chip, struct ttc_pwm_priv, chip);
+}
+
+static void ttc_pwm_enable(struct ttc_pwm_priv *priv, struct pwm_device *pwm)
+{
+	u32 ctrl_reg;
+
+	ctrl_reg = ttc_pwm_ch_readl(priv, pwm, TTC_CNT_CNTRL_OFFSET);
+	ctrl_reg |= (TTC_CNTR_CTRL_INTR_MODE_EN_MASK
+				 | TTC_CNTR_CTRL_MATCH_MODE_EN_MASK | TTC_CNTR_CTRL_RST_MASK);
+	ctrl_reg &= (~(TTC_CNTR_CTRL_DIS_MASK | TTC_CNTR_CTRL_WAVE_EN_MASK));
+	ttc_pwm_ch_writel(priv, pwm, TTC_CNT_CNTRL_OFFSET, ctrl_reg);
+}
+
+static void ttc_pwm_disable(struct ttc_pwm_priv *priv, struct pwm_device *pwm)
+{
+	u32 ctrl_reg;
+
+	ctrl_reg = ttc_pwm_ch_readl(priv, pwm, TTC_CNT_CNTRL_OFFSET);
+	ctrl_reg |= TTC_CNTR_CTRL_DIS_MASK;
+
+	ttc_pwm_ch_writel(priv, pwm, TTC_CNT_CNTRL_OFFSET, ctrl_reg);
+}
+
+static void ttc_pwm_rev_polarity(struct ttc_pwm_priv *priv, struct pwm_device *pwm)
+{
+	u32 ctrl_reg;
+
+	ctrl_reg = ttc_pwm_ch_readl(priv, pwm, TTC_CNT_CNTRL_OFFSET);
+	ctrl_reg ^= TTC_CNTR_CTRL_WAVE_POL_MASK;
+	ttc_pwm_ch_writel(priv, pwm, TTC_CNT_CNTRL_OFFSET, ctrl_reg);
+}
+
+static void ttc_pwm_set_counters(struct ttc_pwm_priv *priv,
+				 struct pwm_device *pwm,
+				 u32 div,
+				 u32 period_cycles,
+				 u32 duty_cycles)
+{
+	u32 clk_reg;
+
+	/* Set up prescalar */
+	clk_reg = ttc_pwm_ch_readl(priv, pwm, TTC_CLK_CNTRL_OFFSET);
+	clk_reg &= ~TTC_CLK_CNTRL_PSV_MASK;
+	clk_reg |= div;
+	ttc_pwm_ch_writel(priv, pwm, TTC_CLK_CNTRL_OFFSET, clk_reg);
+
+	/* Set up period */
+	ttc_pwm_ch_writel(priv, pwm, TTC_INTR_VAL_OFFSET, period_cycles);
+
+	/* Set up duty cycle */
+	ttc_pwm_ch_writel(priv, pwm, TTC_MATCH_CNT_VAL_OFFSET, duty_cycles);
+}
+
+static int ttc_pwm_apply(struct pwm_chip *chip,
+			 struct pwm_device *pwm,
+			 const struct pwm_state *state)
+{
+	u32 div = 0;
+	u64 period_cycles;
+	u64 duty_cycles;
+	unsigned long rate;
+	struct pwm_state cstate;
+	struct ttc_pwm_priv *priv = xilinx_pwm_chip_to_priv(chip);
+
+	pwm_get_state(pwm, &cstate);
+
+	if (state->polarity != cstate.polarity) {
+		if (cstate.enabled)
+			ttc_pwm_disable(priv, pwm);
+
+		ttc_pwm_rev_polarity(priv, pwm);
+
+		if (cstate.enabled)
+			ttc_pwm_enable(priv, pwm);
+	}
+
+	if (state->period != cstate.period ||
+	    state->duty_cycle != cstate.duty_cycle) {
+		rate = clk_get_rate(priv->clk);
+
+		/* Prevent overflow by limiting to the maximum possible period */
+		period_cycles = min_t(u64, state->period, ULONG_MAX * NSEC_PER_SEC);
+		period_cycles = DIV_ROUND_CLOSEST(period_cycles * rate, NSEC_PER_SEC);
+
+		if (period_cycles > priv->max) {
+			/* prescale frequency to fit requested period cycles within limit */
+			div = 1;
+
+			while ((period_cycles  > priv->max) && (div < 65536)) {
+				rate = DIV_ROUND_CLOSEST(rate, BIT(div));
+				period_cycles = DIV_ROUND_CLOSEST(state->period * rate,
+								  NSEC_PER_SEC);
+				if (period_cycles < priv->max)
+					break;
+				div++;
+			}
+
+			if (period_cycles  > priv->max)
+				return -ERANGE;
+		}
+
+		duty_cycles = DIV_ROUND_CLOSEST(state->duty_cycle * rate,
+						NSEC_PER_SEC);
+		if (cstate.enabled)
+			ttc_pwm_disable(priv, pwm);
+
+		ttc_pwm_set_counters(priv, pwm, div, period_cycles, duty_cycles);
+
+		if (cstate.enabled)
+			ttc_pwm_enable(priv, pwm);
+	}
+
+	if (state->enabled != cstate.enabled) {
+		if (state->enabled)
+			ttc_pwm_enable(priv, pwm);
+		else
+			ttc_pwm_disable(priv, pwm);
+	}
+
+	return 0;
+}
+
+static int ttc_pwm_get_state(struct pwm_chip *chip,
+			     struct pwm_device *pwm,
+			     struct pwm_state *state)
+{
+	struct ttc_pwm_priv *priv = xilinx_pwm_chip_to_priv(chip);
+	unsigned long rate;
+	u32 value;
+	u64 tmp;
+
+	value = ttc_pwm_ch_readl(priv, pwm, TTC_CNT_CNTRL_OFFSET);
+
+	if (value & TTC_CNTR_CTRL_WAVE_POL_MASK)
+		state->polarity = PWM_POLARITY_INVERSED;
+	else
+		state->polarity = PWM_POLARITY_NORMAL;
+
+	if (value & TTC_CNTR_CTRL_DIS_MASK)
+		state->enabled = false;
+	else
+		state->enabled = true;
+
+	rate = clk_get_rate(priv->clk);
+
+	tmp = ttc_pwm_ch_readl(priv, pwm, TTC_INTR_VAL_OFFSET);
+	state->period = DIV_ROUND_CLOSEST_ULL(tmp, rate);
+
+	tmp = ttc_pwm_ch_readl(priv, pwm, TTC_MATCH_CNT_VAL_OFFSET);
+	state->duty_cycle = DIV_ROUND_CLOSEST_ULL(tmp, rate);
+
+	return 0;
+}
+
+static struct pwm_device *
+ttc_pwm_of_xlate(struct pwm_chip *chip, const struct of_phandle_args *args)
+{
+	struct pwm_device *pwm;
+
+	if (args->args[0] >= TTC_PWM_MAX_CH)
+		return NULL;
+
+	pwm = pwm_request_from_chip(chip, args->args[0], NULL);
+	if (IS_ERR(pwm))
+		return pwm;
+
+	if (args->args[1])
+		pwm->args.period = args->args[1];
+
+	if (args->args[2])
+		pwm->args.polarity = args->args[2];
+
+	return pwm;
+}
+
+static const struct pwm_ops ttc_pwm_ops = {
+	.apply = ttc_pwm_apply,
+	.get_state = ttc_pwm_get_state,
+	.owner = THIS_MODULE,
+};
+
+static int ttc_pwm_probe(struct platform_device *pdev)
+{
+	int ret;
+	int clksel;
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+	struct ttc_pwm_priv *priv;
+	u32 pwm_cells;
+	u32 timer_width;
+	struct clk *clk_cs;
+
+	ret = of_property_read_u32(np, "#pwm-cells", &pwm_cells);
+	if (ret == -EINVAL)
+		return -ENODEV;
+
+	if (ret)
+		return dev_err_probe(dev, ret, "could not read #pwm-cells\n");
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(priv->base))
+		return PTR_ERR(priv->base);
+
+	ret = of_property_read_u32(np, "timer-width", &timer_width);
+	if (ret)
+		timer_width = 16;
+
+	priv->max = BIT(timer_width) - 1;
+
+	clksel = ttc_pwm_readl(priv, TTC_CLK_CNTRL_OFFSET);
+	clksel = !!(clksel & TTC_CLK_CNTRL_CSRC_MASK);
+	clk_cs = of_clk_get(np, clksel);
+	if (IS_ERR(clk_cs))
+		return dev_err_probe(dev, PTR_ERR(clk_cs),
+				     "ERROR: timer input clock not found\n");
+
+	priv->clk = clk_cs;
+	ret = clk_prepare_enable(priv->clk);
+	if (ret)
+		return dev_err_probe(dev, ret, "Clock enable failed\n");
+
+	clk_rate_exclusive_get(priv->clk);
+
+	priv->chip.dev = dev;
+	priv->chip.ops = &ttc_pwm_ops;
+	priv->chip.npwm = TTC_PWM_MAX_CH;
+	priv->chip.of_xlate = ttc_pwm_of_xlate;
+	ret = pwmchip_add(&priv->chip);
+	if (ret) {
+		clk_rate_exclusive_put(priv->clk);
+		clk_disable_unprepare(priv->clk);
+		return dev_err_probe(dev, ret, "Could not register PWM chip\n");
+	}
+
+	platform_set_drvdata(pdev, priv);
+
+	return 0;
+}
+
+static int ttc_pwm_remove(struct platform_device *pdev)
+{
+	struct ttc_pwm_priv *priv = platform_get_drvdata(pdev);
+
+	pwmchip_remove(&priv->chip);
+	clk_rate_exclusive_put(priv->clk);
+	clk_disable_unprepare(priv->clk);
+
+	return 0;
+}
+
+static const struct of_device_id ttc_pwm_of_match[] = {
+	{ .compatible = "cdns,ttc"},
+	{},
+};
+MODULE_DEVICE_TABLE(of, ttc_pwm_of_match);
+
+static struct platform_driver ttc_pwm_driver = {
+	.probe = ttc_pwm_probe,
+	.remove = ttc_pwm_remove,
+	.driver = {
+		.name = "ttc-pwm",
+		.of_match_table = of_match_ptr(ttc_pwm_of_match),
+	},
+};
+module_platform_driver(ttc_pwm_driver);
+
+MODULE_AUTHOR("Mubin Sayyed <mubin.sayyed@xxxxxxx>");
+MODULE_DESCRIPTION("Cadence TTC PWM driver");
+MODULE_LICENSE("GPL");
-- 
2.25.1