diff options
Diffstat (limited to 'drivers/pwm/pwm-loongson.c')
| -rw-r--r-- | drivers/pwm/pwm-loongson.c | 290 |
1 files changed, 290 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-loongson.c b/drivers/pwm/pwm-loongson.c new file mode 100644 index 000000000000..1ba16168cbb4 --- /dev/null +++ b/drivers/pwm/pwm-loongson.c @@ -0,0 +1,290 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2017-2025 Loongson Technology Corporation Limited. + * + * Loongson PWM driver + * + * For Loongson's PWM IP block documentation please refer Chapter 11 of + * Reference Manual: https://loongson.github.io/LoongArch-Documentation/Loongson-7A1000-usermanual-EN.pdf + * + * Author: Juxin Gao <gaojuxin@loongson.cn> + * Further cleanup and restructuring by: + * Binbin Zhou <zhoubinbin@loongson.cn> + * + * Limitations: + * - If both DUTY and PERIOD are set to 0, the output is a constant low signal. + * - When disabled the output is driven to 0 independent of the configured + * polarity. + * - If the register is reconfigured while PWM is running, it does not complete + * the currently running period. + * - Disabling the PWM stops the output immediately (without waiting for current + * period to complete first). + */ + +#include <linux/acpi.h> +#include <linux/clk.h> +#include <linux/device.h> +#include <linux/init.h> +#include <linux/io.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/platform_device.h> +#include <linux/pwm.h> +#include <linux/units.h> + +/* Loongson PWM registers */ +#define LOONGSON_PWM_REG_DUTY 0x4 /* Low Pulse Buffer Register */ +#define LOONGSON_PWM_REG_PERIOD 0x8 /* Pulse Period Buffer Register */ +#define LOONGSON_PWM_REG_CTRL 0xc /* Control Register */ + +/* Control register bits */ +#define LOONGSON_PWM_CTRL_REG_EN BIT(0) /* Counter Enable Bit */ +#define LOONGSON_PWM_CTRL_REG_OE BIT(3) /* Pulse Output Enable Control Bit, Valid Low */ +#define LOONGSON_PWM_CTRL_REG_SINGLE BIT(4) /* Single Pulse Control Bit */ +#define LOONGSON_PWM_CTRL_REG_INTE BIT(5) /* Interrupt Enable Bit */ +#define LOONGSON_PWM_CTRL_REG_INT BIT(6) /* Interrupt Bit */ +#define LOONGSON_PWM_CTRL_REG_RST BIT(7) /* Counter Reset Bit */ +#define LOONGSON_PWM_CTRL_REG_CAPTE BIT(8) /* Measurement Pulse Enable Bit */ +#define LOONGSON_PWM_CTRL_REG_INVERT BIT(9) /* Output flip-flop Enable Bit */ +#define LOONGSON_PWM_CTRL_REG_DZONE BIT(10) /* Anti-dead Zone Enable Bit */ + +/* default input clk frequency for the ACPI case */ +#define LOONGSON_PWM_FREQ_DEFAULT 50000 /* Hz */ + +struct pwm_loongson_ddata { + struct clk *clk; + void __iomem *base; + u64 clk_rate; +}; + +static inline __pure struct pwm_loongson_ddata *to_pwm_loongson_ddata(struct pwm_chip *chip) +{ + return pwmchip_get_drvdata(chip); +} + +static inline u32 pwm_loongson_readl(struct pwm_loongson_ddata *ddata, u32 offset) +{ + return readl(ddata->base + offset); +} + +static inline void pwm_loongson_writel(struct pwm_loongson_ddata *ddata, + u32 val, u32 offset) +{ + writel(val, ddata->base + offset); +} + +static int pwm_loongson_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm, + enum pwm_polarity polarity) +{ + u16 val; + struct pwm_loongson_ddata *ddata = to_pwm_loongson_ddata(chip); + + val = pwm_loongson_readl(ddata, LOONGSON_PWM_REG_CTRL); + + if (polarity == PWM_POLARITY_INVERSED) + /* Duty cycle defines LOW period of PWM */ + val |= LOONGSON_PWM_CTRL_REG_INVERT; + else + /* Duty cycle defines HIGH period of PWM */ + val &= ~LOONGSON_PWM_CTRL_REG_INVERT; + + pwm_loongson_writel(ddata, val, LOONGSON_PWM_REG_CTRL); + + return 0; +} + +static void pwm_loongson_disable(struct pwm_chip *chip, struct pwm_device *pwm) +{ + u32 val; + struct pwm_loongson_ddata *ddata = to_pwm_loongson_ddata(chip); + + val = pwm_loongson_readl(ddata, LOONGSON_PWM_REG_CTRL); + val &= ~LOONGSON_PWM_CTRL_REG_EN; + pwm_loongson_writel(ddata, val, LOONGSON_PWM_REG_CTRL); +} + +static int pwm_loongson_enable(struct pwm_chip *chip, struct pwm_device *pwm) +{ + u32 val; + struct pwm_loongson_ddata *ddata = to_pwm_loongson_ddata(chip); + + val = pwm_loongson_readl(ddata, LOONGSON_PWM_REG_CTRL); + val |= LOONGSON_PWM_CTRL_REG_EN; + pwm_loongson_writel(ddata, val, LOONGSON_PWM_REG_CTRL); + + return 0; +} + +static int pwm_loongson_config(struct pwm_chip *chip, struct pwm_device *pwm, + u64 duty_ns, u64 period_ns) +{ + u64 duty, period; + struct pwm_loongson_ddata *ddata = to_pwm_loongson_ddata(chip); + + /* duty = duty_ns * ddata->clk_rate / NSEC_PER_SEC */ + duty = mul_u64_u64_div_u64(duty_ns, ddata->clk_rate, NSEC_PER_SEC); + if (duty > U32_MAX) + duty = U32_MAX; + + /* period = period_ns * ddata->clk_rate / NSEC_PER_SEC */ + period = mul_u64_u64_div_u64(period_ns, ddata->clk_rate, NSEC_PER_SEC); + if (period > U32_MAX) + period = U32_MAX; + + pwm_loongson_writel(ddata, duty, LOONGSON_PWM_REG_DUTY); + pwm_loongson_writel(ddata, period, LOONGSON_PWM_REG_PERIOD); + + return 0; +} + +static int pwm_loongson_apply(struct pwm_chip *chip, struct pwm_device *pwm, + const struct pwm_state *state) +{ + int ret; + bool enabled = pwm->state.enabled; + + if (!state->enabled) { + if (enabled) + pwm_loongson_disable(chip, pwm); + return 0; + } + + ret = pwm_loongson_set_polarity(chip, pwm, state->polarity); + if (ret) + return ret; + + ret = pwm_loongson_config(chip, pwm, state->duty_cycle, state->period); + if (ret) + return ret; + + if (!enabled && state->enabled) + ret = pwm_loongson_enable(chip, pwm); + + return ret; +} + +static int pwm_loongson_get_state(struct pwm_chip *chip, struct pwm_device *pwm, + struct pwm_state *state) +{ + u32 duty, period, ctrl; + struct pwm_loongson_ddata *ddata = to_pwm_loongson_ddata(chip); + + duty = pwm_loongson_readl(ddata, LOONGSON_PWM_REG_DUTY); + period = pwm_loongson_readl(ddata, LOONGSON_PWM_REG_PERIOD); + ctrl = pwm_loongson_readl(ddata, LOONGSON_PWM_REG_CTRL); + + /* duty & period have a max of 2^32, so we can't overflow */ + state->duty_cycle = DIV64_U64_ROUND_UP((u64)duty * NSEC_PER_SEC, ddata->clk_rate); + state->period = DIV64_U64_ROUND_UP((u64)period * NSEC_PER_SEC, ddata->clk_rate); + state->polarity = (ctrl & LOONGSON_PWM_CTRL_REG_INVERT) ? PWM_POLARITY_INVERSED : + PWM_POLARITY_NORMAL; + state->enabled = (ctrl & LOONGSON_PWM_CTRL_REG_EN) ? true : false; + + return 0; +} + +static const struct pwm_ops pwm_loongson_ops = { + .apply = pwm_loongson_apply, + .get_state = pwm_loongson_get_state, +}; + +static int pwm_loongson_probe(struct platform_device *pdev) +{ + int ret; + struct pwm_chip *chip; + struct pwm_loongson_ddata *ddata; + struct device *dev = &pdev->dev; + + chip = devm_pwmchip_alloc(dev, 1, sizeof(*ddata)); + if (IS_ERR(chip)) + return PTR_ERR(chip); + ddata = to_pwm_loongson_ddata(chip); + + ddata->base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(ddata->base)) + return PTR_ERR(ddata->base); + + ddata->clk = devm_clk_get_optional_enabled(dev, NULL); + if (IS_ERR(ddata->clk)) + return dev_err_probe(dev, PTR_ERR(ddata->clk), + "Failed to get pwm clock\n"); + if (ddata->clk) { + ret = devm_clk_rate_exclusive_get(dev, ddata->clk); + if (ret) + return dev_err_probe(dev, ret, + "Failed to get exclusive rate\n"); + + ddata->clk_rate = clk_get_rate(ddata->clk); + if (!ddata->clk_rate) + return dev_err_probe(dev, -EINVAL, + "Failed to get frequency\n"); + } else { + ddata->clk_rate = LOONGSON_PWM_FREQ_DEFAULT; + } + + /* This check is done to prevent an overflow in .apply */ + if (ddata->clk_rate > NSEC_PER_SEC) + return dev_err_probe(dev, -EINVAL, "PWM clock out of range\n"); + + chip->ops = &pwm_loongson_ops; + chip->atomic = true; + dev_set_drvdata(dev, chip); + + ret = devm_pwmchip_add(dev, chip); + if (ret < 0) + return dev_err_probe(dev, ret, "Failed to add PWM chip\n"); + + return 0; +} + +static int pwm_loongson_suspend(struct device *dev) +{ + struct pwm_chip *chip = dev_get_drvdata(dev); + struct pwm_loongson_ddata *ddata = to_pwm_loongson_ddata(chip); + struct pwm_device *pwm = &chip->pwms[0]; + + if (pwm->state.enabled) + return -EBUSY; + + clk_disable_unprepare(ddata->clk); + + return 0; +} + +static int pwm_loongson_resume(struct device *dev) +{ + struct pwm_chip *chip = dev_get_drvdata(dev); + struct pwm_loongson_ddata *ddata = to_pwm_loongson_ddata(chip); + + return clk_prepare_enable(ddata->clk); +} + +static DEFINE_SIMPLE_DEV_PM_OPS(pwm_loongson_pm_ops, pwm_loongson_suspend, + pwm_loongson_resume); + +static const struct of_device_id pwm_loongson_of_ids[] = { + { .compatible = "loongson,ls7a-pwm" }, + { /* sentinel */ }, +}; +MODULE_DEVICE_TABLE(of, pwm_loongson_of_ids); + +static const struct acpi_device_id pwm_loongson_acpi_ids[] = { + { "LOON0006" }, + { } +}; +MODULE_DEVICE_TABLE(acpi, pwm_loongson_acpi_ids); + +static struct platform_driver pwm_loongson_driver = { + .probe = pwm_loongson_probe, + .driver = { + .name = "loongson-pwm", + .pm = pm_ptr(&pwm_loongson_pm_ops), + .of_match_table = pwm_loongson_of_ids, + .acpi_match_table = pwm_loongson_acpi_ids, + }, +}; +module_platform_driver(pwm_loongson_driver); + +MODULE_DESCRIPTION("Loongson PWM driver"); +MODULE_AUTHOR("Loongson Technology Corporation Limited."); +MODULE_LICENSE("GPL"); |