[PATCH v6 2/2] pwm: add support for NXPs high-side switch MC33XS2410

[Dimitri Fedrau <dima.fedrau@gmail.com>]

The MC33XS2410 is a four channel high-side switch. Featuring advanced
monitoring and control function, the device is operational from 3.0 V to
60 V. The device is controlled by SPI port for configuration.

Signed-off-by: Dimitri Fedrau <dima.fedrau@gmail.com>
---
 drivers/pwm/Kconfig          |  12 +
 drivers/pwm/Makefile         |   1 +
 drivers/pwm/pwm-mc33xs2410.c | 422 +++++++++++++++++++++++++++++++++++
 3 files changed, 435 insertions(+)
 create mode 100644 drivers/pwm/pwm-mc33xs2410.c

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 0915c1e7df16..f513513f9b2f 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -411,6 +411,18 @@ config PWM_LPSS_PLATFORM
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-lpss-platform.
 
+config PWM_MC33XS2410
+	tristate "MC33XS2410 PWM support"
+	depends on OF
+	depends on SPI
+	help
+	  NXP MC33XS2410 high-side switch driver. The MC33XS2410 is a four
+	  channel high-side switch. The device is operational from 3.0 V
+	  to 60 V. The device is controlled by SPI port for configuration.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-mc33xs2410.
+
 config PWM_MESON
 	tristate "Amlogic Meson PWM driver"
 	depends on ARCH_MESON || COMPILE_TEST
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index 9081e0c0e9e0..c75deeeace40 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -36,6 +36,7 @@ obj-$(CONFIG_PWM_LPC32XX)	+= pwm-lpc32xx.o
 obj-$(CONFIG_PWM_LPSS)		+= pwm-lpss.o
 obj-$(CONFIG_PWM_LPSS_PCI)	+= pwm-lpss-pci.o
 obj-$(CONFIG_PWM_LPSS_PLATFORM)	+= pwm-lpss-platform.o
+obj-$(CONFIG_PWM_MC33XS2410)	+= pwm-mc33xs2410.o
 obj-$(CONFIG_PWM_MESON)		+= pwm-meson.o
 obj-$(CONFIG_PWM_MEDIATEK)	+= pwm-mediatek.o
 obj-$(CONFIG_PWM_MICROCHIP_CORE)	+= pwm-microchip-core.o
diff --git a/drivers/pwm/pwm-mc33xs2410.c b/drivers/pwm/pwm-mc33xs2410.c
new file mode 100644
index 000000000000..f9a334a5e69b
--- /dev/null
+++ b/drivers/pwm/pwm-mc33xs2410.c
@@ -0,0 +1,422 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2024 Liebherr-Electronics and Drives GmbH
+ *
+ * Reference Manual : https://www.nxp.com/docs/en/data-sheet/MC33XS2410.pdf
+ *
+ * Limitations:
+ * - Supports frequencies between 0.5Hz and 2048Hz with following steps:
+ *   - 0.5 Hz steps from 0.5 Hz to 32 Hz
+ *   - 2 Hz steps from 2 Hz to 128 Hz
+ *   - 8 Hz steps from 8 Hz to 512 Hz
+ *   - 32 Hz steps from 32 Hz to 2048 Hz
+ * - Cannot generate a 0 % duty cycle.
+ * - Always produces low output if disabled.
+ * - Configuration isn't atomic. When changing polarity, duty cycle or period
+ *   the data is taken immediately, counters not being affected, resulting in a
+ *   behavior of the output pin that is neither the old nor the new state,
+ *   rather something in between.
+ */
+
+#include <linux/bitfield.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/math64.h>
+#include <linux/minmax.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/pwm.h>
+
+#include <asm/unaligned.h>
+
+#include <linux/spi/spi.h>
+
+#define MC33XS2410_GLB_CTRL		0x00
+#define MC33XS2410_GLB_CTRL_MODE	GENMASK(7, 6)
+#define MC33XS2410_GLB_CTRL_MODE_NORMAL	FIELD_PREP(MC33XS2410_GLB_CTRL_MODE, 1)
+#define MC33XS2410_PWM_CTRL1		0x05
+#define MC33XS2410_PWM_CTRL1_POL_INV(x)	BIT(x)
+#define MC33XS2410_PWM_CTRL3		0x07
+/* x in { 0 ... 3 } */
+#define MC33XS2410_PWM_CTRL3_EN(x)	BIT(4 + (x))
+#define MC33XS2410_PWM_FREQ1		0x08
+/* x in { 1 ... 4 } */
+#define MC33XS2410_PWM_FREQ(x)		(MC33XS2410_PWM_FREQ1 + (x - 1))
+#define MC33XS2410_PWM_FREQ_STEP_MASK	GENMASK(7, 6)
+#define MC33XS2410_PWM_FREQ_COUNT_MASK	GENMASK(5, 0)
+#define MC33XS2410_PWM_DC1		0x0c
+/* x in { 1 ... 4 } */
+#define MC33XS2410_PWM_DC(x)		(MC33XS2410_PWM_DC1 + (x - 1))
+#define MC33XS2410_WDT			0x14
+
+#define MC33XS2410_WR			BIT(7)
+#define MC33XS2410_RD_CTRL		BIT(7)
+#define MC33XS2410_RD_DATA_MASK		GENMASK(13, 0)
+
+#define MC33XS2410_MIN_PERIOD		488282
+#define MC33XS2410_MAX_PERIOD_STEP0	2000000000
+/* x in { 0 ... 3 } */
+#define MC33XS2410_MAX_PERIOD_STEP(x)	(MC33XS2410_MAX_PERIOD_STEP0 >> (2 * x))
+
+#define MC33XS2410_MAX_TRANSFERS	5
+#define MC33XS2410_WORD_LEN		2
+
+struct mc33xs2410_pwm {
+	struct spi_device *spi;
+};
+
+static inline struct mc33xs2410_pwm *mc33xs2410_from_chip(struct pwm_chip *chip)
+{
+	return pwmchip_get_drvdata(chip);
+}
+
+static int mc33xs2410_xfer_regs(struct spi_device *spi, bool read, u8 *reg,
+				u16 *val, bool *ctrl, int len)
+{
+	struct spi_transfer t[MC33XS2410_MAX_TRANSFERS] = { { 0 } };
+	u8 tx[MC33XS2410_MAX_TRANSFERS * MC33XS2410_WORD_LEN];
+	u8 rx[MC33XS2410_MAX_TRANSFERS * MC33XS2410_WORD_LEN];
+	int i, ret, reg_i, val_i;
+
+	if (!len)
+		return 0;
+
+	if (read)
+		len++;
+
+	if (len > MC33XS2410_MAX_TRANSFERS)
+		return -EINVAL;
+
+	for (i = 0; i < len; i++) {
+		reg_i = i * MC33XS2410_WORD_LEN;
+		val_i = reg_i + 1;
+		if (read) {
+			if (i < len - 1) {
+				tx[reg_i] = reg[i];
+				tx[val_i] = ctrl[i] ? MC33XS2410_RD_CTRL : 0;
+				t[i].tx_buf = &tx[reg_i];
+			}
+
+			if (i > 0)
+				t[i].rx_buf = &rx[reg_i - MC33XS2410_WORD_LEN];
+		} else {
+			tx[reg_i] = reg[i] | MC33XS2410_WR;
+			tx[val_i] = val[i];
+			t[i].tx_buf = &tx[reg_i];
+		}
+
+		t[i].len = MC33XS2410_WORD_LEN;
+		t[i].cs_change = 1;
+	}
+
+	t[len - 1].cs_change = 0;
+
+	ret = spi_sync_transfer(spi, &t[0], len);
+	if (ret < 0)
+		return ret;
+
+	if (read) {
+		for (i = 0; i < len - 1; i++) {
+			reg_i = i * MC33XS2410_WORD_LEN;
+			val[i] = FIELD_GET(MC33XS2410_RD_DATA_MASK,
+					   get_unaligned_be16(&rx[reg_i]));
+		}
+	}
+
+	return 0;
+}
+
+static
+int mc33xs2410_write_regs(struct spi_device *spi, u8 *reg, u16 *val, int len)
+{
+
+	return mc33xs2410_xfer_regs(spi, false, reg, val, NULL, len);
+}
+
+static int mc33xs2410_read_regs(struct spi_device *spi, u8 *reg, bool *ctrl,
+				u16 *val, u8 len)
+{
+	return mc33xs2410_xfer_regs(spi, true, reg, val, ctrl, len);
+}
+
+
+static int mc33xs2410_write_reg(struct spi_device *spi, u8 reg, u16 val)
+{
+	return mc33xs2410_write_regs(spi, &reg, &val, 1);
+}
+
+static
+int mc33xs2410_read_reg(struct spi_device *spi, u8 reg, u16 *val, bool ctrl)
+{
+	return mc33xs2410_read_regs(spi, &reg, &ctrl, val, 1);
+}
+
+static int mc33xs2410_read_reg_ctrl(struct spi_device *spi, u8 reg, u16 *val)
+{
+	return mc33xs2410_read_reg(spi, reg, val, true);
+}
+
+static
+int mc33xs2410_modify_reg(struct spi_device *spi, u8 reg, u16 mask, u16 val)
+{
+	u16 tmp;
+	int ret;
+
+	ret = mc33xs2410_read_reg_ctrl(spi, reg, &tmp);
+	if (ret < 0)
+		return ret;
+
+	tmp &= ~mask;
+	tmp |= val & mask;
+
+	return mc33xs2410_write_reg(spi, reg, tmp);
+}
+
+static u8 mc33xs2410_pwm_get_freq(u64 period)
+{
+	u8 step, count;
+
+	/*
+	 * Check which step is appropriate for the given period, starting with
+	 * the highest frequency(lowest period). Higher frequencies are
+	 * represented with better resolution by the device. Therefore favor
+	 * frequency range with the better resolution to minimize error
+	 * introduced by the frequency steps.
+	 */
+
+	switch (period) {
+	case MC33XS2410_MIN_PERIOD ... MC33XS2410_MAX_PERIOD_STEP(3):
+		step = 3;
+		break;
+	case MC33XS2410_MAX_PERIOD_STEP(3) + 1 ... MC33XS2410_MAX_PERIOD_STEP(2):
+		step = 2;
+		break;
+	case MC33XS2410_MAX_PERIOD_STEP(2) + 1 ... MC33XS2410_MAX_PERIOD_STEP(1):
+		step = 1;
+		break;
+	case MC33XS2410_MAX_PERIOD_STEP(1) + 1 ... MC33XS2410_MAX_PERIOD_STEP(0):
+		step = 0;
+		break;
+	}
+
+	/*
+	 * Round up here because a higher count results in a higher frequency
+	 * and so a smaller period.
+	 */
+	count = DIV_ROUND_UP((u32)MC33XS2410_MAX_PERIOD_STEP(step), (u32)period);
+	return FIELD_PREP(MC33XS2410_PWM_FREQ_STEP_MASK, step) |
+	       FIELD_PREP(MC33XS2410_PWM_FREQ_COUNT_MASK, count - 1);
+}
+
+static u64 mc33xs2410_pwm_get_period(u8 reg)
+{
+	u32 freq, code, doubled_steps;
+
+	/*
+	 * steps:
+	 *   - 0 = 0.5Hz
+	 *   - 1 = 2Hz
+	 *   - 2 = 8Hz
+	 *   - 3 = 32Hz
+	 * frequency = (code + 1) x steps.
+	 *
+	 * To avoid losing precision in case steps value is zero, scale the
+	 * steps value for now by two and keep it in mind when calculating the
+	 * period that the frequency had been doubled.
+	 */
+	doubled_steps = 1 << (FIELD_GET(MC33XS2410_PWM_FREQ_STEP_MASK, reg) * 2);
+	code = FIELD_GET(MC33XS2410_PWM_FREQ_COUNT_MASK, reg);
+	freq = (code + 1) * doubled_steps;
+
+	/* Convert frequency to period, considering the doubled frequency. */
+	return DIV_ROUND_UP((u32)(2 * NSEC_PER_SEC), freq);
+}
+
+static int mc33xs2410_pwm_get_relative_duty_cycle(u64 period, u64 duty_cycle)
+{
+	/*
+	 * duty_cycle cannot overflow and period is not zero, since this is
+	 * guaranteed by the caller.
+	 */
+	duty_cycle *= 256;
+	duty_cycle = div64_u64(duty_cycle, period);
+
+	return duty_cycle - 1;
+}
+
+static void mc33xs2410_pwm_set_relative_duty_cycle(struct pwm_state *state,
+						   u16 duty_cycle)
+{
+	if (!state->enabled)
+		state->duty_cycle = 0;
+	else
+		state->duty_cycle = DIV_ROUND_UP_ULL((duty_cycle + 1) * state->period, 256);
+}
+
+static int mc33xs2410_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+				const struct pwm_state *state)
+{
+	struct mc33xs2410_pwm *mc33xs2410 = mc33xs2410_from_chip(chip);
+	struct spi_device *spi = mc33xs2410->spi;
+	u8 reg[4] = {
+			MC33XS2410_PWM_FREQ(pwm->hwpwm + 1),
+			MC33XS2410_PWM_DC(pwm->hwpwm + 1),
+			MC33XS2410_PWM_CTRL1,
+			MC33XS2410_PWM_CTRL3
+		    };
+	bool ctrl[2] = { true, true };
+	u64 period, duty_cycle;
+	int ret, rel_dc;
+	u16 val[4];
+	u8 mask;
+
+	period = min(state->period, MC33XS2410_MAX_PERIOD_STEP(0));
+	if (period < MC33XS2410_MIN_PERIOD)
+		return -EINVAL;
+
+	ret = mc33xs2410_read_regs(spi, &reg[2], &ctrl[0], &val[2], 2);
+	if (ret < 0)
+		return ret;
+
+	/* frequency */
+	val[0] = mc33xs2410_pwm_get_freq(period);
+	/* Continue calculations with the possibly truncated period */
+	period = mc33xs2410_pwm_get_period(val[0]);
+
+	/* duty cycle */
+	duty_cycle = min(period, state->duty_cycle);
+	rel_dc = mc33xs2410_pwm_get_relative_duty_cycle(period, duty_cycle);
+	val[1] = rel_dc < 0 ? 0 : rel_dc;
+
+	/* polarity */
+	mask = MC33XS2410_PWM_CTRL1_POL_INV(pwm->hwpwm);
+	val[2] = (state->polarity == PWM_POLARITY_INVERSED) ?
+		 (val[2] | mask) : (val[2] & ~mask);
+
+	/* enable output */
+	mask = MC33XS2410_PWM_CTRL3_EN(pwm->hwpwm);
+	val[3] = (state->enabled && rel_dc >= 0) ? (val[3] | mask) :
+						   (val[3] & ~mask);
+
+	return mc33xs2410_write_regs(spi, reg, val, 4);
+}
+
+static int mc33xs2410_pwm_get_state(struct pwm_chip *chip,
+				    struct pwm_device *pwm,
+				    struct pwm_state *state)
+{
+	struct mc33xs2410_pwm *mc33xs2410 = mc33xs2410_from_chip(chip);
+	struct spi_device *spi = mc33xs2410->spi;
+	u8 reg[4] = {
+			MC33XS2410_PWM_FREQ(pwm->hwpwm + 1),
+			MC33XS2410_PWM_DC(pwm->hwpwm + 1),
+			MC33XS2410_PWM_CTRL1,
+			MC33XS2410_PWM_CTRL3,
+		    };
+	bool ctrl[4] = { true, true, true, true };
+	u16 val[4];
+	int ret;
+
+	ret = mc33xs2410_read_regs(spi, reg, ctrl, val, 4);
+	if (ret < 0)
+		return ret;
+
+	state->period = mc33xs2410_pwm_get_period(val[0]);
+	state->polarity = (val[2] & MC33XS2410_PWM_CTRL1_POL_INV(pwm->hwpwm)) ?
+			  PWM_POLARITY_INVERSED : PWM_POLARITY_NORMAL;
+	state->enabled = !!(val[3] & MC33XS2410_PWM_CTRL3_EN(pwm->hwpwm));
+	mc33xs2410_pwm_set_relative_duty_cycle(state, val[1]);
+	return 0;
+}
+
+static const struct pwm_ops mc33xs2410_pwm_ops = {
+	.apply = mc33xs2410_pwm_apply,
+	.get_state = mc33xs2410_pwm_get_state,
+};
+
+static int mc33xs2410_reset(struct device *dev)
+{
+	struct gpio_desc *reset_gpio;
+
+	reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
+	if (IS_ERR_OR_NULL(reset_gpio))
+		return PTR_ERR_OR_ZERO(reset_gpio);
+
+	fsleep(1000);
+	gpiod_set_value_cansleep(reset_gpio, 0);
+	/* Wake-up time */
+	fsleep(10000);
+
+	return 0;
+}
+
+static int mc33xs2410_probe(struct spi_device *spi)
+{
+	struct mc33xs2410_pwm *mc33xs2410;
+	struct device *dev = &spi->dev;
+	struct pwm_chip *chip;
+	int ret;
+
+	chip = devm_pwmchip_alloc(dev, 4, sizeof(*mc33xs2410));
+	if (IS_ERR(chip))
+		return PTR_ERR(chip);
+
+	mc33xs2410 = mc33xs2410_from_chip(chip);
+	mc33xs2410->spi = spi;
+	chip->ops = &mc33xs2410_pwm_ops;
+
+	ret = mc33xs2410_reset(dev);
+	if (ret)
+		return ret;
+
+	/*
+	 * Disable watchdog and keep in mind that the watchdog won't trigger a
+	 * reset of the machine when running into an timeout, instead the
+	 * control over the outputs is handed over to the INx input logic
+	 * signals of the device. Disabling it here just deactivates this
+	 * feature until a proper solution is found.
+	 */
+	ret = mc33xs2410_write_reg(spi, MC33XS2410_WDT, 0x0);
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "Failed to disable watchdog\n");
+
+	/* Transition to normal mode */
+	ret = mc33xs2410_modify_reg(spi, MC33XS2410_GLB_CTRL,
+				    MC33XS2410_GLB_CTRL_MODE,
+				    MC33XS2410_GLB_CTRL_MODE_NORMAL);
+	if (ret < 0)
+		return dev_err_probe(dev, ret,
+				     "Failed to transition to normal mode\n");
+
+	ret = devm_pwmchip_add(dev, chip);
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "Failed to add pwm chip\n");
+
+	return 0;
+}
+
+static const struct spi_device_id mc33xs2410_spi_id[] = {
+	{ "mc33xs2410" },
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, mc33xs2410_spi_id);
+
+static const struct of_device_id mc33xs2410_of_match[] = {
+	{ .compatible = "nxp,mc33xs2410" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, mc33xs2410_of_match);
+
+static struct spi_driver mc33xs2410_driver = {
+	.driver = {
+		.name = "mc33xs2410-pwm",
+		.of_match_table = mc33xs2410_of_match,
+	},
+	.probe = mc33xs2410_probe,
+	.id_table = mc33xs2410_spi_id,
+};
+module_spi_driver(mc33xs2410_driver);
+
+MODULE_DESCRIPTION("NXP MC33XS2410 high-side switch driver");
+MODULE_AUTHOR("Dimitri Fedrau <dima.fedrau@gmail.com>");
+MODULE_LICENSE("GPL");
-- 
2.39.5