pwm: adp5585: Add Analog Devices ADP5585 support

The ADP5585 is a 10/11 input/output port expander with a built in keypad
matrix decoder, programmable logic, reset generator, and PWM generator.
This driver supports the PWM function using the platform device
registered by the core MFD driver.

The driver is derived from an initial implementation from NXP, available
in commit 113113742208 ("MLK-25922-1 pwm: adp5585: add adp5585 PWM
support") in their BSP kernel tree. It has been extensively rewritten.

Signed-off-by: Clark Wang <xiaoning.wang@nxp.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Co-developed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Uwe Kleine-König <ukleinek@kernel.org>
Link: https://lore.kernel.org/r/20240722121100.2855-5-laurent.pinchart@ideasonboard.com
Signed-off-by: Lee Jones <lee@kernel.org>

MAINTAINERS

@@ -545,6 +545,7 @@ S:	Maintained
 F:	Documentation/devicetree/bindings/*/adi,adp5585*.yaml
 F:	drivers/gpio/gpio-adp5585.c
 F:	drivers/mfd/adp5585.c
+F:	drivers/pwm/pwm-adp5585.c
 F:	include/linux/mfd/adp5585.h
 
 ADP5588 QWERTY KEYPAD AND IO EXPANDER DRIVER (ADP5588/ADP5587)

drivers/pwm/Kconfig

@@ -47,6 +47,13 @@ config PWM_AB8500
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-ab8500.
 
+config PWM_ADP5585
+	tristate "ADP5585 PWM support"
+	depends on MFD_ADP5585
+	help
+	  This option enables support for the PWM function found in the Analog
+	  Devices ADP5585.
+
 config PWM_APPLE
 	tristate "Apple SoC PWM support"
 	depends on ARCH_APPLE || COMPILE_TEST

drivers/pwm/Makefile

@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 obj-$(CONFIG_PWM)		+= core.o
 obj-$(CONFIG_PWM_AB8500)	+= pwm-ab8500.o
+obj-$(CONFIG_PWM_ADP5585)	+= pwm-adp5585.o
 obj-$(CONFIG_PWM_APPLE)		+= pwm-apple.o
 obj-$(CONFIG_PWM_ATMEL)		+= pwm-atmel.o
 obj-$(CONFIG_PWM_ATMEL_HLCDC_PWM)	+= pwm-atmel-hlcdc.o

drivers/pwm/pwm-adp5585.c

@@ -0,0 +1,184 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Analog Devices ADP5585 PWM driver
+ *
+ * Copyright 2022 NXP
+ * Copyright 2024 Ideas on Board Oy
+ *
+ * Limitations:
+ * - The .apply() operation executes atomically, but may not wait for the
+ *   period to complete (this is not documented and would need to be tested).
+ * - Disabling the PWM drives the output pin to a low level immediately.
+ * - The hardware can only generate normal polarity output.
+ */
+
+#include <asm/byteorder.h>
+
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/math64.h>
+#include <linux/mfd/adp5585.h>
+#include <linux/minmax.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/regmap.h>
+#include <linux/time.h>
+#include <linux/types.h>
+
+#define ADP5585_PWM_CHAN_NUM		1
+
+#define ADP5585_PWM_OSC_FREQ_HZ		1000000U
+#define ADP5585_PWM_MIN_PERIOD_NS	(2ULL * NSEC_PER_SEC / ADP5585_PWM_OSC_FREQ_HZ)
+#define ADP5585_PWM_MAX_PERIOD_NS	(2ULL * 0xffff * NSEC_PER_SEC / ADP5585_PWM_OSC_FREQ_HZ)
+
+static int pwm_adp5585_request(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct regmap *regmap = pwmchip_get_drvdata(chip);
+
+	/* Configure the R3 pin as PWM output. */
+	return regmap_update_bits(regmap, ADP5585_PIN_CONFIG_C,
+				  ADP5585_R3_EXTEND_CFG_MASK,
+				  ADP5585_R3_EXTEND_CFG_PWM_OUT);
+}
+
+static void pwm_adp5585_free(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct regmap *regmap = pwmchip_get_drvdata(chip);
+
+	regmap_update_bits(regmap, ADP5585_PIN_CONFIG_C,
+			   ADP5585_R3_EXTEND_CFG_MASK,
+			   ADP5585_R3_EXTEND_CFG_GPIO4);
+}
+
+static int pwm_adp5585_apply(struct pwm_chip *chip,
+			     struct pwm_device *pwm,
+			     const struct pwm_state *state)
+{
+	struct regmap *regmap = pwmchip_get_drvdata(chip);
+	u64 period, duty_cycle;
+	u32 on, off;
+	__le16 val;
+	int ret;
+
+	if (!state->enabled) {
+		regmap_clear_bits(regmap, ADP5585_GENERAL_CFG, ADP5585_OSC_EN);
+		regmap_clear_bits(regmap, ADP5585_PWM_CFG, ADP5585_PWM_EN);
+		return 0;
+	}
+
+	if (state->polarity != PWM_POLARITY_NORMAL)
+		return -EINVAL;
+
+	if (state->period < ADP5585_PWM_MIN_PERIOD_NS)
+		return -EINVAL;
+
+	period = min(state->period, ADP5585_PWM_MAX_PERIOD_NS);
+	duty_cycle = min(state->duty_cycle, period);
+
+	/*
+	 * Compute the on and off time. As the internal oscillator frequency is
+	 * 1MHz, the calculation can be simplified without loss of precision.
+	 */
+	on = div_u64(duty_cycle, NSEC_PER_SEC / ADP5585_PWM_OSC_FREQ_HZ);
+	off = div_u64(period, NSEC_PER_SEC / ADP5585_PWM_OSC_FREQ_HZ) - on;
+
+	val = cpu_to_le16(off);
+	ret = regmap_bulk_write(regmap, ADP5585_PWM_OFFT_LOW, &val, 2);
+	if (ret)
+		return ret;
+
+	val = cpu_to_le16(on);
+	ret = regmap_bulk_write(regmap, ADP5585_PWM_ONT_LOW, &val, 2);
+	if (ret)
+		return ret;
+
+	/* Enable PWM in continuous mode and no external AND'ing. */
+	ret = regmap_update_bits(regmap, ADP5585_PWM_CFG,
+				 ADP5585_PWM_IN_AND | ADP5585_PWM_MODE |
+				 ADP5585_PWM_EN, ADP5585_PWM_EN);
+	if (ret)
+		return ret;
+
+	return regmap_set_bits(regmap, ADP5585_PWM_CFG, ADP5585_PWM_EN);
+}
+
+static int pwm_adp5585_get_state(struct pwm_chip *chip,
+				 struct pwm_device *pwm,
+				 struct pwm_state *state)
+{
+	struct regmap *regmap = pwmchip_get_drvdata(chip);
+	unsigned int on, off;
+	unsigned int val;
+	__le16 on_off;
+	int ret;
+
+	ret = regmap_bulk_read(regmap, ADP5585_PWM_OFFT_LOW, &on_off, 2);
+	if (ret)
+		return ret;
+	off = le16_to_cpu(on_off);
+
+	ret = regmap_bulk_read(regmap, ADP5585_PWM_ONT_LOW, &on_off, 2);
+	if (ret)
+		return ret;
+	on = le16_to_cpu(on_off);
+
+	state->duty_cycle = on * (NSEC_PER_SEC / ADP5585_PWM_OSC_FREQ_HZ);
+	state->period = (on + off) * (NSEC_PER_SEC / ADP5585_PWM_OSC_FREQ_HZ);
+
+	state->polarity = PWM_POLARITY_NORMAL;
+
+	regmap_read(regmap, ADP5585_PWM_CFG, &val);
+	state->enabled = !!(val & ADP5585_PWM_EN);
+
+	return 0;
+}
+
+static const struct pwm_ops adp5585_pwm_ops = {
+	.request = pwm_adp5585_request,
+	.free = pwm_adp5585_free,
+	.apply = pwm_adp5585_apply,
+	.get_state = pwm_adp5585_get_state,
+};
+
+static int adp5585_pwm_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct adp5585_dev *adp5585 = dev_get_drvdata(dev->parent);
+	struct pwm_chip *chip;
+	int ret;
+
+	chip = devm_pwmchip_alloc(dev, ADP5585_PWM_CHAN_NUM, 0);
+	if (IS_ERR(chip))
+		return PTR_ERR(chip);
+
+	device_set_of_node_from_dev(dev, dev->parent);
+
+	pwmchip_set_drvdata(chip, adp5585->regmap);
+	chip->ops = &adp5585_pwm_ops;
+
+	ret = devm_pwmchip_add(dev, chip);
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to add PWM chip\n");
+
+	return 0;
+}
+
+static const struct platform_device_id adp5585_pwm_id_table[] = {
+	{ "adp5585-pwm" },
+	{ /* Sentinel */ }
+};
+MODULE_DEVICE_TABLE(platform, adp5585_pwm_id_table);
+
+static struct platform_driver adp5585_pwm_driver = {
+	.driver	= {
+		.name = "adp5585-pwm",
+	},
+	.probe = adp5585_pwm_probe,
+	.id_table = adp5585_pwm_id_table,
+};
+module_platform_driver(adp5585_pwm_driver);
+
+MODULE_AUTHOR("Xiaoning Wang <xiaoning.wang@nxp.com>");
+MODULE_DESCRIPTION("ADP5585 PWM Driver");
+MODULE_LICENSE("GPL");