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- // SPDX-License-Identifier: GPL-2.0-only
- /*
- * drivers/pwm/pwm-vt8500.c
- *
- * Copyright (C) 2012 Tony Prisk <[email protected]>
- * Copyright (C) 2010 Alexey Charkov <[email protected]>
- */
- #include <linux/module.h>
- #include <linux/kernel.h>
- #include <linux/platform_device.h>
- #include <linux/slab.h>
- #include <linux/err.h>
- #include <linux/io.h>
- #include <linux/pwm.h>
- #include <linux/delay.h>
- #include <linux/clk.h>
- #include <asm/div64.h>
- #include <linux/of.h>
- #include <linux/of_device.h>
- #include <linux/of_address.h>
- /*
- * SoC architecture allocates register space for 4 PWMs but only
- * 2 are currently implemented.
- */
- #define VT8500_NR_PWMS 2
- #define REG_CTRL(pwm) (((pwm) << 4) + 0x00)
- #define REG_SCALAR(pwm) (((pwm) << 4) + 0x04)
- #define REG_PERIOD(pwm) (((pwm) << 4) + 0x08)
- #define REG_DUTY(pwm) (((pwm) << 4) + 0x0C)
- #define REG_STATUS 0x40
- #define CTRL_ENABLE BIT(0)
- #define CTRL_INVERT BIT(1)
- #define CTRL_AUTOLOAD BIT(2)
- #define CTRL_STOP_IMM BIT(3)
- #define CTRL_LOAD_PRESCALE BIT(4)
- #define CTRL_LOAD_PERIOD BIT(5)
- #define STATUS_CTRL_UPDATE BIT(0)
- #define STATUS_SCALAR_UPDATE BIT(1)
- #define STATUS_PERIOD_UPDATE BIT(2)
- #define STATUS_DUTY_UPDATE BIT(3)
- #define STATUS_ALL_UPDATE 0x0F
- struct vt8500_chip {
- struct pwm_chip chip;
- void __iomem *base;
- struct clk *clk;
- };
- #define to_vt8500_chip(chip) container_of(chip, struct vt8500_chip, chip)
- #define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t)
- static inline void vt8500_pwm_busy_wait(struct vt8500_chip *vt8500, int nr, u8 bitmask)
- {
- int loops = msecs_to_loops(10);
- u32 mask = bitmask << (nr << 8);
- while ((readl(vt8500->base + REG_STATUS) & mask) && --loops)
- cpu_relax();
- if (unlikely(!loops))
- dev_warn(vt8500->chip.dev, "Waiting for status bits 0x%x to clear timed out\n",
- mask);
- }
- static int vt8500_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
- u64 duty_ns, u64 period_ns)
- {
- struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
- unsigned long long c;
- unsigned long period_cycles, prescale, pv, dc;
- int err;
- u32 val;
- err = clk_enable(vt8500->clk);
- if (err < 0) {
- dev_err(chip->dev, "failed to enable clock\n");
- return err;
- }
- c = clk_get_rate(vt8500->clk);
- c = c * period_ns;
- do_div(c, 1000000000);
- period_cycles = c;
- if (period_cycles < 1)
- period_cycles = 1;
- prescale = (period_cycles - 1) / 4096;
- pv = period_cycles / (prescale + 1) - 1;
- if (pv > 4095)
- pv = 4095;
- if (prescale > 1023) {
- clk_disable(vt8500->clk);
- return -EINVAL;
- }
- c = (unsigned long long)pv * duty_ns;
- dc = div64_u64(c, period_ns);
- writel(prescale, vt8500->base + REG_SCALAR(pwm->hwpwm));
- vt8500_pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_SCALAR_UPDATE);
- writel(pv, vt8500->base + REG_PERIOD(pwm->hwpwm));
- vt8500_pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_PERIOD_UPDATE);
- writel(dc, vt8500->base + REG_DUTY(pwm->hwpwm));
- vt8500_pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_DUTY_UPDATE);
- val = readl(vt8500->base + REG_CTRL(pwm->hwpwm));
- val |= CTRL_AUTOLOAD;
- writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
- vt8500_pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);
- clk_disable(vt8500->clk);
- return 0;
- }
- static int vt8500_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
- {
- struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
- int err;
- u32 val;
- err = clk_enable(vt8500->clk);
- if (err < 0) {
- dev_err(chip->dev, "failed to enable clock\n");
- return err;
- }
- val = readl(vt8500->base + REG_CTRL(pwm->hwpwm));
- val |= CTRL_ENABLE;
- writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
- vt8500_pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);
- return 0;
- }
- static void vt8500_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
- {
- struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
- u32 val;
- val = readl(vt8500->base + REG_CTRL(pwm->hwpwm));
- val &= ~CTRL_ENABLE;
- writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
- vt8500_pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);
- clk_disable(vt8500->clk);
- }
- static int vt8500_pwm_set_polarity(struct pwm_chip *chip,
- struct pwm_device *pwm,
- enum pwm_polarity polarity)
- {
- struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
- u32 val;
- val = readl(vt8500->base + REG_CTRL(pwm->hwpwm));
- if (polarity == PWM_POLARITY_INVERSED)
- val |= CTRL_INVERT;
- else
- val &= ~CTRL_INVERT;
- writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
- vt8500_pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);
- return 0;
- }
- static int vt8500_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
- const struct pwm_state *state)
- {
- int err;
- bool enabled = pwm->state.enabled;
- if (state->polarity != pwm->state.polarity) {
- /*
- * Changing the polarity of a running PWM is only allowed when
- * the PWM driver implements ->apply().
- */
- if (enabled) {
- vt8500_pwm_disable(chip, pwm);
- enabled = false;
- }
- err = vt8500_pwm_set_polarity(chip, pwm, state->polarity);
- if (err)
- return err;
- }
- if (!state->enabled) {
- if (enabled)
- vt8500_pwm_disable(chip, pwm);
- return 0;
- }
- /*
- * We cannot skip calling ->config even if state->period ==
- * pwm->state.period && state->duty_cycle == pwm->state.duty_cycle
- * because we might have exited early in the last call to
- * pwm_apply_state because of !state->enabled and so the two values in
- * pwm->state might not be configured in hardware.
- */
- err = vt8500_pwm_config(pwm->chip, pwm, state->duty_cycle, state->period);
- if (err)
- return err;
- if (!enabled)
- err = vt8500_pwm_enable(chip, pwm);
- return err;
- }
- static const struct pwm_ops vt8500_pwm_ops = {
- .apply = vt8500_pwm_apply,
- .owner = THIS_MODULE,
- };
- static const struct of_device_id vt8500_pwm_dt_ids[] = {
- { .compatible = "via,vt8500-pwm", },
- { /* Sentinel */ }
- };
- MODULE_DEVICE_TABLE(of, vt8500_pwm_dt_ids);
- static int vt8500_pwm_probe(struct platform_device *pdev)
- {
- struct vt8500_chip *vt8500;
- struct device_node *np = pdev->dev.of_node;
- int ret;
- if (!np) {
- dev_err(&pdev->dev, "invalid devicetree node\n");
- return -EINVAL;
- }
- vt8500 = devm_kzalloc(&pdev->dev, sizeof(*vt8500), GFP_KERNEL);
- if (vt8500 == NULL)
- return -ENOMEM;
- vt8500->chip.dev = &pdev->dev;
- vt8500->chip.ops = &vt8500_pwm_ops;
- vt8500->chip.npwm = VT8500_NR_PWMS;
- vt8500->clk = devm_clk_get(&pdev->dev, NULL);
- if (IS_ERR(vt8500->clk)) {
- dev_err(&pdev->dev, "clock source not specified\n");
- return PTR_ERR(vt8500->clk);
- }
- vt8500->base = devm_platform_ioremap_resource(pdev, 0);
- if (IS_ERR(vt8500->base))
- return PTR_ERR(vt8500->base);
- ret = clk_prepare(vt8500->clk);
- if (ret < 0) {
- dev_err(&pdev->dev, "failed to prepare clock\n");
- return ret;
- }
- ret = pwmchip_add(&vt8500->chip);
- if (ret < 0) {
- dev_err(&pdev->dev, "failed to add PWM chip\n");
- clk_unprepare(vt8500->clk);
- return ret;
- }
- platform_set_drvdata(pdev, vt8500);
- return ret;
- }
- static int vt8500_pwm_remove(struct platform_device *pdev)
- {
- struct vt8500_chip *vt8500 = platform_get_drvdata(pdev);
- pwmchip_remove(&vt8500->chip);
- clk_unprepare(vt8500->clk);
- return 0;
- }
- static struct platform_driver vt8500_pwm_driver = {
- .probe = vt8500_pwm_probe,
- .remove = vt8500_pwm_remove,
- .driver = {
- .name = "vt8500-pwm",
- .of_match_table = vt8500_pwm_dt_ids,
- },
- };
- module_platform_driver(vt8500_pwm_driver);
- MODULE_DESCRIPTION("VT8500 PWM Driver");
- MODULE_AUTHOR("Tony Prisk <[email protected]>");
- MODULE_LICENSE("GPL v2");
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