pwm: Add driver for cadence TTC

TTC has three modes of operations. Timer, PWM and input counters.

There is already driver for timer under CADENCE_TTC_TIMER which is used for
ZynqMP R5 configuration.
This driver is targeting PWM which is for example configuration which can
be used for fan control.
The driver has been tested on Xilinx Kria SOM platform where fan is
connected to one PL pin. When TTC output is connected via EMIO to PL pin
TTC pwm can be configured and tested for example like this:
pwm config 0 0 10000 1200
pwm enable 0 0
pwm config 0 0 10000 1400
pwm config 0 0 10000 1600

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Sean Anderson <sean.anderson@seco.com>
Link: https://lore.kernel.org/r/915a662ddb88f7a958ca1f307e8fea59af9d7feb.1634303847.git.michal.simek@xilinx.com

MAINTAINERS

@@ -655,6 +655,7 @@ F:	drivers/net/phy/xilinx_phy.c
 F:	drivers/net/zynq_gem.c
 F:	drivers/phy/phy-zynqmp.c
 F:	drivers/power/domain/zynqmp-power-domain.c
+F:	drivers/pwm/pwm-cadence-ttc.c
 F:	drivers/serial/serial_zynq.c
 F:	drivers/reset/reset-zynqmp.c
 F:	drivers/rtc/zynqmp_rtc.c

drivers/pwm/Kconfig

@@ -23,6 +23,13 @@ config PWM_AT91
 	help
 	  Support for PWM hardware on AT91 based SoC.
 
+config PWM_CADENCE_TTC
+	bool "Enable support for the Cadence TTC PWM"
+	depends on DM_PWM && !CADENCE_TTC_TIMER
+	help
+	  Cadence TTC can be configured as timer which is done via
+	  CONFIG_CADENCE_TTC_TIMER or as PWM. This is covering only PWM now.
+
 config PWM_CROS_EC
 	bool "Enable support for the Chrome OS EC PWM"
 	depends on DM_PWM

drivers/pwm/Makefile

@@ -12,6 +12,7 @@ obj-$(CONFIG_DM_PWM)		+= pwm-uclass.o
 
 obj-$(CONFIG_PWM_ASPEED)	+= pwm-aspeed.o
 obj-$(CONFIG_PWM_AT91)		+= pwm-at91.o
+obj-$(CONFIG_PWM_CADENCE_TTC)	+= pwm-cadence-ttc.o
 obj-$(CONFIG_PWM_CROS_EC)	+= cros_ec_pwm.o
 obj-$(CONFIG_PWM_EXYNOS)	+= exynos_pwm.o
 obj-$(CONFIG_PWM_IMX)		+= pwm-imx.o pwm-imx-util.o

drivers/pwm/pwm-cadence-ttc.c

@@ -0,0 +1,261 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * (C) Copyright 2021 Xilinx, Inc. Michal Simek
+ */
+
+#define LOG_CATEGORY UCLASS_PWM
+
+#include <clk.h>
+#include <common.h>
+#include <div64.h>
+#include <dm.h>
+#include <log.h>
+#include <pwm.h>
+#include <asm/io.h>
+#include <log.h>
+#include <div64.h>
+#include <linux/bitfield.h>
+#include <linux/math64.h>
+#include <linux/log2.h>
+#include <dm/device_compat.h>
+
+#define CLOCK_CONTROL		0
+#define COUNTER_CONTROL		0xc
+#define INTERVAL_COUNTER	0x24
+#define MATCH_1_COUNTER		0x30
+
+#define CLK_FALLING_EDGE	BIT(6)
+#define CLK_SRC_EXTERNAL	BIT(5)
+#define CLK_PRESCALE_MASK	GENMASK(4, 1)
+#define CLK_PRESCALE_ENABLE	BIT(0)
+
+#define COUNTER_WAVE_POL		BIT(6)
+#define COUNTER_WAVE_DISABLE		BIT(5)
+#define COUNTER_RESET			BIT(4)
+#define COUNTER_MATCH_ENABLE		BIT(3)
+#define COUNTER_DECREMENT_ENABLE	BIT(2)
+#define COUNTER_INTERVAL_ENABLE		BIT(1)
+#define COUNTER_COUNTING_DISABLE	BIT(0)
+
+#define NSEC_PER_SEC	1000000000L
+
+#define TTC_REG(reg, channel) ((reg) + (channel) * sizeof(u32))
+#define TTC_CLOCK_CONTROL(reg, channel) \
+	TTC_REG((reg) + CLOCK_CONTROL, (channel))
+#define TTC_COUNTER_CONTROL(reg, channel) \
+	TTC_REG((reg) + COUNTER_CONTROL, (channel))
+#define TTC_INTERVAL_COUNTER(reg, channel) \
+	TTC_REG((reg) + INTERVAL_COUNTER, (channel))
+#define TTC_MATCH_1_COUNTER(reg, channel) \
+	TTC_REG((reg) + MATCH_1_COUNTER, (channel))
+
+struct cadence_ttc_pwm_plat {
+	u8 *regs;
+	u32 timer_width;
+};
+
+struct cadence_ttc_pwm_priv {
+	u8 *regs;
+	u32 timer_width;
+	u32 timer_mask;
+	unsigned long frequency;
+	bool invert[2];
+};
+
+static int cadence_ttc_pwm_set_invert(struct udevice *dev, uint channel,
+				      bool polarity)
+{
+	struct cadence_ttc_pwm_priv *priv = dev_get_priv(dev);
+
+	if (channel > 2) {
+		dev_err(dev, "Unsupported channel number %d(max 2)\n", channel);
+		return -EINVAL;
+	}
+
+	priv->invert[channel] = polarity;
+
+	dev_dbg(dev, "polarity=%u. Please config PWM again\n", polarity);
+
+	return 0;
+}
+
+static int cadence_ttc_pwm_set_config(struct udevice *dev, uint channel,
+				      uint period_ns, uint duty_ns)
+{
+	struct cadence_ttc_pwm_priv *priv = dev_get_priv(dev);
+	u32 counter_ctrl, clock_ctrl;
+	int period_clocks, duty_clocks, prescaler;
+
+	dev_dbg(dev, "channel %d, duty %d/period %d ns\n", channel,
+		duty_ns, period_ns);
+
+	if (channel > 2) {
+		dev_err(dev, "Unsupported channel number %d(max 2)\n", channel);
+		return -EINVAL;
+	}
+
+	/* Make sure counter is stopped */
+	counter_ctrl = readl(TTC_COUNTER_CONTROL(priv->regs, channel));
+	setbits_le32(TTC_COUNTER_CONTROL(priv->regs, channel),
+		     COUNTER_COUNTING_DISABLE | COUNTER_WAVE_DISABLE);
+
+	/* Calculate period, prescaler and set clock control register */
+	period_clocks = div64_u64(((int64_t)period_ns * priv->frequency),
+				  NSEC_PER_SEC);
+
+	prescaler = ilog2(period_clocks) + 1 - priv->timer_width;
+	if (prescaler < 0)
+		prescaler = 0;
+
+	clock_ctrl = readl(TTC_CLOCK_CONTROL(priv->regs, channel));
+
+	if (!prescaler) {
+		clock_ctrl &= ~(CLK_PRESCALE_ENABLE | CLK_PRESCALE_MASK);
+	} else {
+		clock_ctrl &= ~CLK_PRESCALE_MASK;
+		clock_ctrl |= CLK_PRESCALE_ENABLE;
+		clock_ctrl |= FIELD_PREP(CLK_PRESCALE_MASK, prescaler - 1);
+	};
+
+	/* External source is not handled by this driver now */
+	clock_ctrl &= ~CLK_SRC_EXTERNAL;
+
+	writel(clock_ctrl, TTC_CLOCK_CONTROL(priv->regs, channel));
+
+	/* Calculate interval and set counter control value */
+	duty_clocks = div64_u64(((int64_t)duty_ns * priv->frequency),
+				NSEC_PER_SEC);
+
+	writel((period_clocks >> prescaler) & priv->timer_mask,
+	       TTC_INTERVAL_COUNTER(priv->regs, channel));
+	writel((duty_clocks >> prescaler) & priv->timer_mask,
+	       TTC_MATCH_1_COUNTER(priv->regs, channel));
+
+	/* Restore/reset counter */
+	counter_ctrl &= ~COUNTER_DECREMENT_ENABLE;
+	counter_ctrl |= COUNTER_INTERVAL_ENABLE |
+			COUNTER_RESET |
+			COUNTER_MATCH_ENABLE;
+
+	if (priv->invert[channel])
+		counter_ctrl |= COUNTER_WAVE_POL;
+	else
+		counter_ctrl &= ~COUNTER_WAVE_POL;
+
+	writel(counter_ctrl, TTC_COUNTER_CONTROL(priv->regs, channel));
+
+	dev_dbg(dev, "%d/%d clocks, prescaler 2^%d\n", duty_clocks,
+		period_clocks, prescaler);
+
+	return 0;
+};
+
+static int cadence_ttc_pwm_set_enable(struct udevice *dev, uint channel,
+				      bool enable)
+{
+	struct cadence_ttc_pwm_priv *priv = dev_get_priv(dev);
+
+	if (channel > 2) {
+		dev_err(dev, "Unsupported channel number %d(max 2)\n", channel);
+		return -EINVAL;
+	}
+
+	dev_dbg(dev, "Enable: %d, channel %d\n", enable, channel);
+
+	if (enable) {
+		clrbits_le32(TTC_COUNTER_CONTROL(priv->regs, channel),
+			     COUNTER_COUNTING_DISABLE |
+			     COUNTER_WAVE_DISABLE);
+		setbits_le32(TTC_COUNTER_CONTROL(priv->regs, channel),
+			     COUNTER_RESET);
+	} else {
+		setbits_le32(TTC_COUNTER_CONTROL(priv->regs, channel),
+			     COUNTER_COUNTING_DISABLE |
+			     COUNTER_WAVE_DISABLE);
+	}
+
+	return 0;
+};
+
+static int cadence_ttc_pwm_probe(struct udevice *dev)
+{
+	struct cadence_ttc_pwm_priv *priv = dev_get_priv(dev);
+	struct cadence_ttc_pwm_plat *plat = dev_get_plat(dev);
+	struct clk clk;
+	int ret;
+
+	priv->regs = plat->regs;
+	priv->timer_width = plat->timer_width;
+	priv->timer_mask = GENMASK(priv->timer_width - 1, 0);
+
+	ret = clk_get_by_index(dev, 0, &clk);
+	if (ret < 0) {
+		dev_err(dev, "failed to get clock\n");
+		return ret;
+	}
+
+	priv->frequency = clk_get_rate(&clk);
+	if (IS_ERR_VALUE(priv->frequency)) {
+		dev_err(dev, "failed to get rate\n");
+		return priv->frequency;
+	}
+	dev_dbg(dev, "Clk frequency: %ld\n", priv->frequency);
+
+	ret = clk_enable(&clk);
+	if (ret) {
+		dev_err(dev, "failed to enable clock\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static int cadence_ttc_pwm_of_to_plat(struct udevice *dev)
+{
+	struct cadence_ttc_pwm_plat *plat = dev_get_plat(dev);
+	const char *cells;
+
+	cells = dev_read_prop(dev, "#pwm-cells", NULL);
+	if (!cells)
+		return -EINVAL;
+
+	plat->regs = dev_read_addr_ptr(dev);
+
+	plat->timer_width = dev_read_u32_default(dev, "timer-width", 16);
+
+	return 0;
+}
+
+static int cadence_ttc_pwm_bind(struct udevice *dev)
+{
+	const char *cells;
+
+	cells = dev_read_prop(dev, "#pwm-cells", NULL);
+	if (!cells)
+		return -ENODEV;
+
+	return 0;
+}
+
+static const struct pwm_ops cadence_ttc_pwm_ops = {
+	.set_invert = cadence_ttc_pwm_set_invert,
+	.set_config = cadence_ttc_pwm_set_config,
+	.set_enable = cadence_ttc_pwm_set_enable,
+};
+
+static const struct udevice_id cadence_ttc_pwm_ids[] = {
+	{ .compatible = "cdns,ttc" },
+	{ }
+};
+
+U_BOOT_DRIVER(cadence_ttc_pwm) = {
+	.name = "cadence_ttc_pwm",
+	.id = UCLASS_PWM,
+	.of_match = cadence_ttc_pwm_ids,
+	.ops = &cadence_ttc_pwm_ops,
+	.bind = cadence_ttc_pwm_bind,
+	.of_to_plat = cadence_ttc_pwm_of_to_plat,
+	.probe = cadence_ttc_pwm_probe,
+	.priv_auto = sizeof(struct cadence_ttc_pwm_priv),
+	.plat_auto = sizeof(struct cadence_ttc_pwm_plat),
+};