diff options
Diffstat (limited to '')
| -rw-r--r-- | drivers/pwm/pwm-tiecap.c | 333 |
1 files changed, 333 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-tiecap.c b/drivers/pwm/pwm-tiecap.c new file mode 100644 index 0000000000..8c94b266c1 --- /dev/null +++ b/drivers/pwm/pwm-tiecap.c @@ -0,0 +1,333 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * ECAP PWM driver + * + * Copyright (C) 2012 Texas Instruments, Inc. - https://www.ti.com/ + */ + +#include <linux/module.h> +#include <linux/platform_device.h> +#include <linux/io.h> +#include <linux/err.h> +#include <linux/clk.h> +#include <linux/pm_runtime.h> +#include <linux/pwm.h> +#include <linux/of.h> + +/* ECAP registers and bits definitions */ +#define CAP1 0x08 +#define CAP2 0x0C +#define CAP3 0x10 +#define CAP4 0x14 +#define ECCTL2 0x2A +#define ECCTL2_APWM_POL_LOW BIT(10) +#define ECCTL2_APWM_MODE BIT(9) +#define ECCTL2_SYNC_SEL_DISA (BIT(7) | BIT(6)) +#define ECCTL2_TSCTR_FREERUN BIT(4) + +struct ecap_context { + u32 cap3; + u32 cap4; + u16 ecctl2; +}; + +struct ecap_pwm_chip { + struct pwm_chip chip; + unsigned int clk_rate; + void __iomem *mmio_base; + struct ecap_context ctx; +}; + +static inline struct ecap_pwm_chip *to_ecap_pwm_chip(struct pwm_chip *chip) +{ + return container_of(chip, struct ecap_pwm_chip, chip); +} + +/* + * period_ns = 10^9 * period_cycles / PWM_CLK_RATE + * duty_ns = 10^9 * duty_cycles / PWM_CLK_RATE + */ +static int ecap_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, + int duty_ns, int period_ns, int enabled) +{ + struct ecap_pwm_chip *pc = to_ecap_pwm_chip(chip); + u32 period_cycles, duty_cycles; + unsigned long long c; + u16 value; + + c = pc->clk_rate; + c = c * period_ns; + do_div(c, NSEC_PER_SEC); + period_cycles = (u32)c; + + if (period_cycles < 1) { + period_cycles = 1; + duty_cycles = 1; + } else { + c = pc->clk_rate; + c = c * duty_ns; + do_div(c, NSEC_PER_SEC); + duty_cycles = (u32)c; + } + + pm_runtime_get_sync(pc->chip.dev); + + value = readw(pc->mmio_base + ECCTL2); + + /* Configure APWM mode & disable sync option */ + value |= ECCTL2_APWM_MODE | ECCTL2_SYNC_SEL_DISA; + + writew(value, pc->mmio_base + ECCTL2); + + if (!enabled) { + /* Update active registers if not running */ + writel(duty_cycles, pc->mmio_base + CAP2); + writel(period_cycles, pc->mmio_base + CAP1); + } else { + /* + * Update shadow registers to configure period and + * compare values. This helps current PWM period to + * complete on reconfiguring + */ + writel(duty_cycles, pc->mmio_base + CAP4); + writel(period_cycles, pc->mmio_base + CAP3); + } + + if (!enabled) { + value = readw(pc->mmio_base + ECCTL2); + /* Disable APWM mode to put APWM output Low */ + value &= ~ECCTL2_APWM_MODE; + writew(value, pc->mmio_base + ECCTL2); + } + + pm_runtime_put_sync(pc->chip.dev); + + return 0; +} + +static int ecap_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm, + enum pwm_polarity polarity) +{ + struct ecap_pwm_chip *pc = to_ecap_pwm_chip(chip); + u16 value; + + pm_runtime_get_sync(pc->chip.dev); + + value = readw(pc->mmio_base + ECCTL2); + + if (polarity == PWM_POLARITY_INVERSED) + /* Duty cycle defines LOW period of PWM */ + value |= ECCTL2_APWM_POL_LOW; + else + /* Duty cycle defines HIGH period of PWM */ + value &= ~ECCTL2_APWM_POL_LOW; + + writew(value, pc->mmio_base + ECCTL2); + + pm_runtime_put_sync(pc->chip.dev); + + return 0; +} + +static int ecap_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) +{ + struct ecap_pwm_chip *pc = to_ecap_pwm_chip(chip); + u16 value; + + /* Leave clock enabled on enabling PWM */ + pm_runtime_get_sync(pc->chip.dev); + + /* + * Enable 'Free run Time stamp counter mode' to start counter + * and 'APWM mode' to enable APWM output + */ + value = readw(pc->mmio_base + ECCTL2); + value |= ECCTL2_TSCTR_FREERUN | ECCTL2_APWM_MODE; + writew(value, pc->mmio_base + ECCTL2); + + return 0; +} + +static void ecap_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) +{ + struct ecap_pwm_chip *pc = to_ecap_pwm_chip(chip); + u16 value; + + /* + * Disable 'Free run Time stamp counter mode' to stop counter + * and 'APWM mode' to put APWM output to low + */ + value = readw(pc->mmio_base + ECCTL2); + value &= ~(ECCTL2_TSCTR_FREERUN | ECCTL2_APWM_MODE); + writew(value, pc->mmio_base + ECCTL2); + + /* Disable clock on PWM disable */ + pm_runtime_put_sync(pc->chip.dev); +} + +static int ecap_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, + const struct pwm_state *state) +{ + int err; + int enabled = pwm->state.enabled; + + if (state->polarity != pwm->state.polarity) { + + if (enabled) { + ecap_pwm_disable(chip, pwm); + enabled = false; + } + + err = ecap_pwm_set_polarity(chip, pwm, state->polarity); + if (err) + return err; + } + + if (!state->enabled) { + if (enabled) + ecap_pwm_disable(chip, pwm); + return 0; + } + + if (state->period > NSEC_PER_SEC) + return -ERANGE; + + err = ecap_pwm_config(chip, pwm, state->duty_cycle, + state->period, enabled); + if (err) + return err; + + if (!enabled) + return ecap_pwm_enable(chip, pwm); + + return 0; +} + +static const struct pwm_ops ecap_pwm_ops = { + .apply = ecap_pwm_apply, + .owner = THIS_MODULE, +}; + +static const struct of_device_id ecap_of_match[] = { + { .compatible = "ti,am3352-ecap" }, + { .compatible = "ti,am33xx-ecap" }, + {}, +}; +MODULE_DEVICE_TABLE(of, ecap_of_match); + +static int ecap_pwm_probe(struct platform_device *pdev) +{ + struct device_node *np = pdev->dev.of_node; + struct ecap_pwm_chip *pc; + struct clk *clk; + int ret; + + pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL); + if (!pc) + return -ENOMEM; + + clk = devm_clk_get(&pdev->dev, "fck"); + if (IS_ERR(clk)) { + if (of_device_is_compatible(np, "ti,am33xx-ecap")) { + dev_warn(&pdev->dev, "Binding is obsolete.\n"); + clk = devm_clk_get(pdev->dev.parent, "fck"); + } + } + + if (IS_ERR(clk)) { + dev_err(&pdev->dev, "failed to get clock\n"); + return PTR_ERR(clk); + } + + pc->clk_rate = clk_get_rate(clk); + if (!pc->clk_rate) { + dev_err(&pdev->dev, "failed to get clock rate\n"); + return -EINVAL; + } + + pc->chip.dev = &pdev->dev; + pc->chip.ops = &ecap_pwm_ops; + pc->chip.npwm = 1; + + pc->mmio_base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(pc->mmio_base)) + return PTR_ERR(pc->mmio_base); + + ret = devm_pwmchip_add(&pdev->dev, &pc->chip); + if (ret < 0) { + dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret); + return ret; + } + + platform_set_drvdata(pdev, pc); + pm_runtime_enable(&pdev->dev); + + return 0; +} + +static void ecap_pwm_remove(struct platform_device *pdev) +{ + pm_runtime_disable(&pdev->dev); +} + +#ifdef CONFIG_PM_SLEEP +static void ecap_pwm_save_context(struct ecap_pwm_chip *pc) +{ + pm_runtime_get_sync(pc->chip.dev); + pc->ctx.ecctl2 = readw(pc->mmio_base + ECCTL2); + pc->ctx.cap4 = readl(pc->mmio_base + CAP4); + pc->ctx.cap3 = readl(pc->mmio_base + CAP3); + pm_runtime_put_sync(pc->chip.dev); +} + +static void ecap_pwm_restore_context(struct ecap_pwm_chip *pc) +{ + writel(pc->ctx.cap3, pc->mmio_base + CAP3); + writel(pc->ctx.cap4, pc->mmio_base + CAP4); + writew(pc->ctx.ecctl2, pc->mmio_base + ECCTL2); +} + +static int ecap_pwm_suspend(struct device *dev) +{ + struct ecap_pwm_chip *pc = dev_get_drvdata(dev); + struct pwm_device *pwm = pc->chip.pwms; + + ecap_pwm_save_context(pc); + + /* Disable explicitly if PWM is running */ + if (pwm_is_enabled(pwm)) + pm_runtime_put_sync(dev); + + return 0; +} + +static int ecap_pwm_resume(struct device *dev) +{ + struct ecap_pwm_chip *pc = dev_get_drvdata(dev); + struct pwm_device *pwm = pc->chip.pwms; + + /* Enable explicitly if PWM was running */ + if (pwm_is_enabled(pwm)) + pm_runtime_get_sync(dev); + + ecap_pwm_restore_context(pc); + return 0; +} +#endif + +static SIMPLE_DEV_PM_OPS(ecap_pwm_pm_ops, ecap_pwm_suspend, ecap_pwm_resume); + +static struct platform_driver ecap_pwm_driver = { + .driver = { + .name = "ecap", + .of_match_table = ecap_of_match, + .pm = &ecap_pwm_pm_ops, + }, + .probe = ecap_pwm_probe, + .remove_new = ecap_pwm_remove, +}; +module_platform_driver(ecap_pwm_driver); + +MODULE_DESCRIPTION("ECAP PWM driver"); +MODULE_AUTHOR("Texas Instruments"); +MODULE_LICENSE("GPL"); |