[PATCH 2/2] pwm: add Axiado AX3000 PWM driver

[Petar Stepanovic]

The Axiado AX3000 and AX3005 SoCs include PWM controllers that can be
used to generate configurable PWM output signals.

Add a PWM driver with support for configuring period, duty cycle, and
enable state through the Linux PWM framework.

Signed-off-by: Petar Stepanovic <pstepanovic@xxxxxxxxxx>
---
 MAINTAINERS              |   1 +
 drivers/pwm/Kconfig      |  11 +++
 drivers/pwm/Makefile     |   1 +
 drivers/pwm/pwm-axiado.c | 193 +++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 206 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 394c4a3527e8..db93fc235c32 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4319,6 +4319,7 @@ M:	Prasad Bolisetty <pbolisetty@xxxxxxxxxx>
 L:	linux-pwm@xxxxxxxxxxxxxxx
 S:	Maintained
 F:	Documentation/devicetree/bindings/pwm/axiado,ax3000-pwm.yaml
+F:	drivers/pwm/pwm-axiado.c
 
 AXIS ARTPEC ARM64 SoC SUPPORT
 M:	Jesper Nilsson <jesper.nilsson@xxxxxxxx>
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 6f3147518376..76f6c04b0e23 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -129,6 +129,17 @@ config PWM_ATMEL_TCB
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-atmel-tcb.
 
+config PWM_AXIADO
+	tristate "Axiado PWM support"
+	depends on ARCH_AXIADO || COMPILE_TEST
+	depends on HAS_IOMEM
+	help
+	  PWM framework driver for the PWM controller found on Axiado
+	  AX3000 and AX3005 SoCs.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-axiado.
+
 config PWM_AXI_PWMGEN
 	tristate "Analog Devices AXI PWM generator"
 	depends on MICROBLAZE || NIOS2 || ARCH_ZYNQ || ARCH_ZYNQMP || ARCH_INTEL_SOCFPGA || COMPILE_TEST
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index 0dc0d2b69025..4466a29e780a 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -8,6 +8,7 @@ obj-$(CONFIG_PWM_ARGON_FAN_HAT)	+= pwm-argon-fan-hat.o
 obj-$(CONFIG_PWM_ATMEL)		+= pwm-atmel.o
 obj-$(CONFIG_PWM_ATMEL_HLCDC_PWM)	+= pwm-atmel-hlcdc.o
 obj-$(CONFIG_PWM_ATMEL_TCB)	+= pwm-atmel-tcb.o
+obj-$(CONFIG_PWM_AXIADO)	+= pwm-axiado.o
 obj-$(CONFIG_PWM_AXI_PWMGEN)	+= pwm-axi-pwmgen.o
 obj-$(CONFIG_PWM_BCM2835)	+= pwm-bcm2835.o
 obj-$(CONFIG_PWM_BCM_IPROC)	+= pwm-bcm-iproc.o
diff --git a/drivers/pwm/pwm-axiado.c b/drivers/pwm/pwm-axiado.c
new file mode 100644
index 000000000000..db197886c5c4
--- /dev/null
+++ b/drivers/pwm/pwm-axiado.c
@@ -0,0 +1,193 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2021-2026 Axiado Corporation.
+ */
+
+#include <linux/bits.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/math64.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+
+/* Register offsets */
+#define AX_PWM_CNTRL_REG     0x0000
+#define AX_PWM_PERIOD_REG    0x0004
+#define AX_PWM_HIGH_REG      0x0008
+
+/* PWM channels */
+#define AX_PWM_NUM 1
+
+/* Period and duty cycle limits */
+#define AX_PWM_PERIOD_MIN       2
+#define AX_PWM_PERIOD_MAX       0xfffffffeU
+#define AX_PWM_DUTY_MIN         1
+#define AX_PWM_DUTY_MAX         0xfffffffdU
+
+/* Control register bits */
+#define AX_PWM_CTRL_ENABLE BIT(0)
+#define AX_PWM_CTRL_DISABLE 0x0
+
+struct axiado_pwm_chip {
+	struct clk *clk;
+	void __iomem *base;
+};
+
+static int axiado_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
+			     u64 duty_ns, u64 period_ns)
+{
+	struct axiado_pwm_chip *axpwm = pwmchip_get_drvdata(chip);
+	unsigned long rate;
+	u64 period_cycles, duty_cycles;
+
+	/*
+	 * The hardware does not support a zero period, 0% duty cycle, or
+	 * 100% duty cycle. The caller should handle 0% duty cycle by
+	 * disabling the PWM.
+	 */
+	if (!period_ns || !duty_ns || duty_ns >= period_ns)
+		return -EINVAL;
+
+	rate = clk_get_rate(axpwm->clk);
+	if (!rate)
+		return -EINVAL;
+
+	period_cycles = mul_u64_u64_div_u64(period_ns, rate, NSEC_PER_SEC);
+	if (period_cycles < AX_PWM_PERIOD_MIN ||
+	    period_cycles > AX_PWM_PERIOD_MAX)
+		return -EINVAL;
+
+	duty_cycles = mul_u64_u64_div_u64(duty_ns, rate, NSEC_PER_SEC);
+	if (duty_cycles < AX_PWM_DUTY_MIN ||
+	    duty_cycles > AX_PWM_DUTY_MAX)
+		return -EINVAL;
+
+	if (duty_cycles >= period_cycles)
+		return -EINVAL;
+
+	writel((u32)period_cycles, axpwm->base + AX_PWM_PERIOD_REG);
+	writel((u32)duty_cycles, axpwm->base + AX_PWM_HIGH_REG);
+
+	return 0;
+}
+
+static int axiado_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+			    const struct pwm_state *state)
+{
+	struct axiado_pwm_chip *axpwm = pwmchip_get_drvdata(chip);
+	int ret;
+
+	if (state->polarity != PWM_POLARITY_NORMAL)
+		return -EINVAL;
+
+	if (!state->enabled || !state->duty_cycle) {
+		if (pwm->state.enabled)
+			writel(AX_PWM_CTRL_DISABLE, axpwm->base + AX_PWM_CNTRL_REG);
+
+		return 0;
+	}
+
+	ret = axiado_pwm_config(chip, pwm, state->duty_cycle, state->period);
+	if (ret)
+		return ret;
+
+	if (!pwm->state.enabled)
+		writel(AX_PWM_CTRL_ENABLE, axpwm->base + AX_PWM_CNTRL_REG);
+
+	return 0;
+}
+
+static int axiado_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+				struct pwm_state *state)
+{
+	struct axiado_pwm_chip *axpwm = pwmchip_get_drvdata(chip);
+	unsigned long rate;
+	u32 period_cycles;
+	u32 duty_cycles;
+	u32 ctrl;
+
+	rate = clk_get_rate(axpwm->clk);
+	if (!rate)
+		return -EINVAL;
+
+	ctrl = readl(axpwm->base + AX_PWM_CNTRL_REG);
+	period_cycles = readl(axpwm->base + AX_PWM_PERIOD_REG);
+	duty_cycles = readl(axpwm->base + AX_PWM_HIGH_REG);
+
+	state->enabled = !!(ctrl & AX_PWM_CTRL_ENABLE);
+	state->period = mul_u64_u64_div_u64(period_cycles, NSEC_PER_SEC, rate);
+	state->duty_cycle = mul_u64_u64_div_u64(duty_cycles, NSEC_PER_SEC, rate);
+	state->polarity = PWM_POLARITY_NORMAL;
+
+	return 0;
+}
+
+static const struct pwm_ops axiado_pwm_ops = {
+	.get_state = axiado_pwm_get_state,
+	.apply = axiado_pwm_apply,
+};
+
+static void axiado_pwm_disable(void *data)
+{
+	struct axiado_pwm_chip *axpwm = data;
+
+	writel(AX_PWM_CTRL_DISABLE, axpwm->base + AX_PWM_CNTRL_REG);
+}
+
+static int axiado_pwm_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct axiado_pwm_chip *axpwm;
+	struct pwm_chip *chip;
+	int ret;
+
+	chip = devm_pwmchip_alloc(dev, AX_PWM_NUM, sizeof(*axpwm));
+	if (IS_ERR(chip))
+		return PTR_ERR(chip);
+
+	axpwm = pwmchip_get_drvdata(chip);
+
+	axpwm->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(axpwm->base))
+		return dev_err_probe(dev, PTR_ERR(axpwm->base),
+				     "failed to map registers\n");
+
+	ret = devm_add_action_or_reset(dev, axiado_pwm_disable, axpwm);
+	if (ret)
+		return ret;
+
+
+	axpwm->clk = devm_clk_get_enabled(dev, "pwm");
+	if (IS_ERR(axpwm->clk))
+		return dev_err_probe(dev, PTR_ERR(axpwm->clk),
+				     "failed to get/enable clock\n");
+
+	chip->ops = &axiado_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 of_device_id axiado_pwm_match[] = {
+	{ .compatible = "axiado,ax3000-pwm" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, axiado_pwm_match);
+
+static struct platform_driver axiado_pwm_driver = {
+	.driver = {
+		.name =  "axiado-pwm",
+		.of_match_table = axiado_pwm_match,
+	},
+	.probe = axiado_pwm_probe,
+};
+
+module_platform_driver(axiado_pwm_driver);
+
+MODULE_AUTHOR("Axiado Corporation");
+MODULE_DESCRIPTION("Axiado PWM driver");
+MODULE_LICENSE("GPL");

-- 
2.34.1