pwm: opencores: Add PWM driver support

Add driver for OpenCores PWM Controller. And add compatibility code
which based on StarFive SoC.

Co-developed-by: Hal Feng <hal.feng@starfivetech.com>
Signed-off-by: Hal Feng <hal.feng@starfivetech.com>
Signed-off-by: William Qiu <william.qiu@starfivetech.com>
Tested-by: Maud Spierings <maud_spierings@hotmail.com>
Link: https://lore.kernel.org/r/20250106103540.10079-1-william.qiu@starfivetech.com
Signed-off-by: Emil Renner Berthing <emil.renner.berthing@canonical.com>

4 files changed, 258 insertions, 0 deletions

diff --git a/MAINTAINERS b/MAINTAINERS
index efee40ea589f..f398bfae65c0 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -17731,6 +17731,13 @@ F:	Documentation/i2c/busses/i2c-ocores.rst
 F:	drivers/i2c/busses/i2c-ocores.c
 F:	include/linux/platform_data/i2c-ocores.h
 
+OPENCORES PWM DRIVER
+M:	William Qiu <william.qiu@starfivetech.com>
+M:	Hal Feng <hal.feng@starfivetech.com>
+S:	Supported
+F:	Documentation/devicetree/bindings/pwm/opencores,pwm.yaml
+F:	drivers/pwm/pwm-ocores.c
+
 OPENRISC ARCHITECTURE
 M:	Jonas Bonn <jonas@southpole.se>
 M:	Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 0915c1e7df16..33819cb585be 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -471,6 +471,18 @@ config PWM_NTXEC
 	  controller found in certain e-book readers designed by the original
 	  design manufacturer Netronix.
 
+config PWM_OCORES
+	tristate "OpenCores PTC PWM support"
+	depends on HAS_IOMEM && OF
+	depends on COMMON_CLK
+	depends on ARCH_STARFIVE || COMPILE_TEST
+	help
+	  If you say yes to this option, support will be included for the
+	  OpenCores PWM. For details see https://opencores.org/projects/ptc.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-ocores.
+
 config PWM_OMAP_DMTIMER
 	tristate "OMAP Dual-Mode Timer PWM support"
 	depends on OF
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index 9081e0c0e9e0..e55997490dcb 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -42,6 +42,7 @@ obj-$(CONFIG_PWM_MICROCHIP_CORE)	+= pwm-microchip-core.o
 obj-$(CONFIG_PWM_MTK_DISP)	+= pwm-mtk-disp.o
 obj-$(CONFIG_PWM_MXS)		+= pwm-mxs.o
 obj-$(CONFIG_PWM_NTXEC)		+= pwm-ntxec.o
+obj-$(CONFIG_PWM_OCORES)	+= pwm-ocores.o
 obj-$(CONFIG_PWM_OMAP_DMTIMER)	+= pwm-omap-dmtimer.o
 obj-$(CONFIG_PWM_PCA9685)	+= pwm-pca9685.o
 obj-$(CONFIG_PWM_PXA)		+= pwm-pxa.o
diff --git a/drivers/pwm/pwm-ocores.c b/drivers/pwm/pwm-ocores.c
new file mode 100644
index 000000000000..bc957830017f
--- /dev/null
+++ b/drivers/pwm/pwm-ocores.c
@@ -0,0 +1,238 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * OpenCores PWM Driver
+ *
+ * https://opencores.org/projects/ptc
+ *
+ * Copyright (C) 2018-2023 StarFive Technology Co., Ltd.
+ *
+ * Limitations:
+ * - The hardware only supports inverted polarity.
+ * - The hardware minimum period / duty_cycle is (1 / pwm_apb clock frequency).
+ * - The hardware maximum period / duty_cycle is (U32_MAX / pwm_apb clock frequency).
+ * - The output is set to a low level immediately when disabled.
+ * - When configuration changes are done, they get active immediately without resetting
+ *   the counter. This might result in one period affected by both old and new settings.
+ */
+
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/reset.h>
+#include <linux/slab.h>
+
+/* OpenCores Register offsets */
+#define REG_OCPWM_CNTR    0x0
+#define REG_OCPWM_HRC     0x4
+#define REG_OCPWM_LRC     0x8
+#define REG_OCPWM_CTRL    0xC
+
+/* OCPWM_CTRL register bits*/
+#define REG_OCPWM_CNTR_EN      BIT(0)
+#define REG_OCPWM_CNTR_ECLK    BIT(1)
+#define REG_OCPWM_CNTR_NEC     BIT(2)
+#define REG_OCPWM_CNTR_OE      BIT(3)
+#define REG_OCPWM_CNTR_SIGNLE  BIT(4)
+#define REG_OCPWM_CNTR_INTE    BIT(5)
+#define REG_OCPWM_CNTR_INT     BIT(6)
+#define REG_OCPWM_CNTR_RST     BIT(7)
+#define REG_OCPWM_CNTR_CAPTE   BIT(8)
+
+struct ocores_pwm_data {
+	void __iomem *(*get_ch_base)(void __iomem *base, unsigned int channel);
+};
+
+struct ocores_pwm_device {
+	const struct ocores_pwm_data *data;
+	void __iomem *regs;
+	u32 clk_rate; /* PWM APB clock frequency */
+};
+
+static inline u32 ocores_pwm_readl(struct ocores_pwm_device *ddata,
+				   unsigned int channel,
+				   unsigned int offset)
+{
+	void __iomem *base = ddata->data->get_ch_base ?
+			     ddata->data->get_ch_base(ddata->regs, channel) : ddata->regs;
+
+	return readl(base + offset);
+}
+
+static inline void ocores_pwm_writel(struct ocores_pwm_device *ddata,
+				     unsigned int channel,
+				     unsigned int offset, u32 val)
+{
+	void __iomem *base = ddata->data->get_ch_base ?
+			     ddata->data->get_ch_base(ddata->regs, channel) : ddata->regs;
+
+	writel(val, base + offset);
+}
+
+static inline struct ocores_pwm_device *chip_to_ocores(struct pwm_chip *chip)
+{
+	return pwmchip_get_drvdata(chip);
+}
+
+static void __iomem *ocores_pwm_get_ch_base(void __iomem *base,
+					    unsigned int channel)
+{
+	unsigned int offset = (channel & 4) << 13 | (channel & 3) << 4;
+
+	return base + offset;
+}
+
+static int ocores_pwm_get_state(struct pwm_chip *chip,
+				struct pwm_device *pwm,
+				struct pwm_state *state)
+{
+	struct ocores_pwm_device *ddata = chip_to_ocores(chip);
+	u32 period_data, duty_data, ctrl_data;
+
+	period_data = ocores_pwm_readl(ddata, pwm->hwpwm, REG_OCPWM_LRC);
+	duty_data = ocores_pwm_readl(ddata, pwm->hwpwm, REG_OCPWM_HRC);
+	ctrl_data = ocores_pwm_readl(ddata, pwm->hwpwm, REG_OCPWM_CTRL);
+
+	state->period = DIV_ROUND_UP_ULL((u64)period_data * NSEC_PER_SEC, ddata->clk_rate);
+	state->duty_cycle = DIV_ROUND_UP_ULL((u64)duty_data * NSEC_PER_SEC, ddata->clk_rate);
+	state->polarity = PWM_POLARITY_INVERSED;
+	state->enabled = (ctrl_data & REG_OCPWM_CNTR_EN) ? true : false;
+
+	return 0;
+}
+
+static int ocores_pwm_apply(struct pwm_chip *chip,
+			    struct pwm_device *pwm,
+			    const struct pwm_state *state)
+{
+	struct ocores_pwm_device *ddata = chip_to_ocores(chip);
+	u32 ctrl_data = 0;
+	u64 period_data, duty_data;
+
+	if (state->polarity != PWM_POLARITY_INVERSED)
+		return -EINVAL;
+
+	period_data = mul_u64_u32_div(state->period, ddata->clk_rate, NSEC_PER_SEC);
+	if (!period_data)
+		return -EINVAL;
+
+	if (period_data > U32_MAX)
+		period_data = U32_MAX;
+
+	ocores_pwm_writel(ddata, pwm->hwpwm, REG_OCPWM_LRC, period_data);
+
+	duty_data = mul_u64_u32_div(state->duty_cycle, ddata->clk_rate, NSEC_PER_SEC);
+	if (duty_data > U32_MAX)
+		duty_data = U32_MAX;
+
+	ocores_pwm_writel(ddata, pwm->hwpwm, REG_OCPWM_HRC, duty_data);
+
+	ctrl_data = ocores_pwm_readl(ddata, pwm->hwpwm, REG_OCPWM_CTRL);
+	if (state->enabled)
+		ocores_pwm_writel(ddata, pwm->hwpwm, REG_OCPWM_CTRL,
+				  ctrl_data | REG_OCPWM_CNTR_EN | REG_OCPWM_CNTR_OE);
+	else
+		ocores_pwm_writel(ddata, pwm->hwpwm, REG_OCPWM_CTRL,
+				  ctrl_data & ~(REG_OCPWM_CNTR_EN | REG_OCPWM_CNTR_OE));
+
+	return 0;
+}
+
+static const struct pwm_ops ocores_pwm_ops = {
+	.get_state = ocores_pwm_get_state,
+	.apply = ocores_pwm_apply,
+};
+
+static const struct ocores_pwm_data starfive_pwm_data = {
+	.get_ch_base = ocores_pwm_get_ch_base,
+};
+
+static const struct of_device_id ocores_pwm_of_match[] = {
+	{ .compatible = "opencores,pwm-v1" },
+	{ .compatible = "starfive,jh7100-pwm", .data = &starfive_pwm_data},
+	{ .compatible = "starfive,jh7110-pwm", .data = &starfive_pwm_data},
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, ocores_pwm_of_match);
+
+static void ocores_pwm_reset_control_assert(void *data)
+{
+	reset_control_assert(data);
+}
+
+static int ocores_pwm_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct ocores_pwm_device *ddata;
+	struct pwm_chip *chip;
+	struct clk *clk;
+	struct reset_control *rst;
+	int ret;
+
+	chip = devm_pwmchip_alloc(&pdev->dev, 8, sizeof(*ddata));
+	if (IS_ERR(chip))
+		return -ENOMEM;
+
+	ddata = chip_to_ocores(chip);
+	ddata->data = device_get_match_data(&pdev->dev);
+	chip->ops = &ocores_pwm_ops;
+
+	ddata->regs = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(ddata->regs))
+		return dev_err_probe(dev, PTR_ERR(ddata->regs),
+				     "Failed to map IO resources\n");
+
+	clk = devm_clk_get_enabled(dev, NULL);
+	if (IS_ERR(clk))
+		return dev_err_probe(dev, PTR_ERR(clk),
+				     "Failed to get pwm's clock\n");
+
+	ret = devm_clk_rate_exclusive_get(dev, clk);
+	if (ret)
+		return dev_err_probe(dev, ret,
+				     "Failed to lock clock rate\n");
+
+	rst = devm_reset_control_get_optional_exclusive(dev, NULL);
+	if (IS_ERR(rst))
+		return dev_err_probe(dev, PTR_ERR(rst),
+				     "Failed to get pwm's reset\n");
+
+	ret = reset_control_deassert(rst);
+	if (ret) {
+		dev_err(dev, "Failed to deassert pwm's reset\n");
+		return ret;
+	}
+
+	ret = devm_add_action_or_reset(dev, ocores_pwm_reset_control_assert, rst);
+	if (ret) {
+		dev_err(dev, "Failed to register assert devm action\n");
+		return ret;
+	}
+
+	ddata->clk_rate = clk_get_rate(clk);
+	if (ddata->clk_rate > NSEC_PER_SEC) {
+		dev_err(dev, "Failed to get clock frequency\n");
+		return -EINVAL;
+	}
+
+	ret = devm_pwmchip_add(dev, chip);
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "Could not register PWM chip\n");
+
+	return 0;
+}
+
+static struct platform_driver ocores_pwm_driver = {
+	.probe = ocores_pwm_probe,
+	.driver = {
+		.name = "ocores-pwm",
+		.of_match_table = ocores_pwm_of_match,
+	},
+};
+module_platform_driver(ocores_pwm_driver);
+
+MODULE_AUTHOR("Jieqin Chen");
+MODULE_AUTHOR("Hal Feng <hal.feng@starfivetech.com>");
+MODULE_DESCRIPTION("OpenCores PTC PWM driver");
+MODULE_LICENSE("GPL");