diff options
Diffstat (limited to 'drivers/pwm/pwm-pxa.c')
| -rw-r--r-- | drivers/pwm/pwm-pxa.c | 213 |
1 files changed, 213 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-pxa.c b/drivers/pwm/pwm-pxa.c new file mode 100644 index 0000000000..1e475ed101 --- /dev/null +++ b/drivers/pwm/pwm-pxa.c @@ -0,0 +1,213 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * drivers/pwm/pwm-pxa.c + * + * simple driver for PWM (Pulse Width Modulator) controller + * + * 2008-02-13 initial version + * eric miao <eric.miao@marvell.com> + * + * Links to reference manuals for some of the supported PWM chips can be found + * in Documentation/arch/arm/marvell.rst. + * + * Limitations: + * - When PWM is stopped, the current PWM period stops abruptly at the next + * input clock (PWMCR_SD is set) and the output is driven to inactive. + */ + +#include <linux/mod_devicetable.h> +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/platform_device.h> +#include <linux/slab.h> +#include <linux/err.h> +#include <linux/clk.h> +#include <linux/io.h> +#include <linux/pwm.h> +#include <linux/of_device.h> + +#include <asm/div64.h> + +#define HAS_SECONDARY_PWM 0x10 + +static const struct platform_device_id pwm_id_table[] = { + /* PWM has_secondary_pwm? */ + { "pxa25x-pwm", 0 }, + { "pxa27x-pwm", HAS_SECONDARY_PWM }, + { "pxa168-pwm", 0 }, + { "pxa910-pwm", 0 }, + { }, +}; +MODULE_DEVICE_TABLE(platform, pwm_id_table); + +/* PWM registers and bits definitions */ +#define PWMCR (0x00) +#define PWMDCR (0x04) +#define PWMPCR (0x08) + +#define PWMCR_SD (1 << 6) +#define PWMDCR_FD (1 << 10) + +struct pxa_pwm_chip { + struct pwm_chip chip; + struct device *dev; + + struct clk *clk; + void __iomem *mmio_base; +}; + +static inline struct pxa_pwm_chip *to_pxa_pwm_chip(struct pwm_chip *chip) +{ + return container_of(chip, struct pxa_pwm_chip, chip); +} + +/* + * period_ns = 10^9 * (PRESCALE + 1) * (PV + 1) / PWM_CLK_RATE + * duty_ns = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE + */ +static int pxa_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, + u64 duty_ns, u64 period_ns) +{ + struct pxa_pwm_chip *pc = to_pxa_pwm_chip(chip); + unsigned long long c; + unsigned long period_cycles, prescale, pv, dc; + unsigned long offset; + + offset = pwm->hwpwm ? 0x10 : 0; + + c = clk_get_rate(pc->clk); + c = c * period_ns; + do_div(c, 1000000000); + period_cycles = c; + + if (period_cycles < 1) + period_cycles = 1; + prescale = (period_cycles - 1) / 1024; + pv = period_cycles / (prescale + 1) - 1; + + if (prescale > 63) + return -EINVAL; + + if (duty_ns == period_ns) + dc = PWMDCR_FD; + else + dc = mul_u64_u64_div_u64(pv + 1, duty_ns, period_ns); + + writel(prescale | PWMCR_SD, pc->mmio_base + offset + PWMCR); + writel(dc, pc->mmio_base + offset + PWMDCR); + writel(pv, pc->mmio_base + offset + PWMPCR); + + return 0; +} + +static int pxa_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, + const struct pwm_state *state) +{ + struct pxa_pwm_chip *pc = to_pxa_pwm_chip(chip); + u64 duty_cycle; + int err; + + if (state->polarity != PWM_POLARITY_NORMAL) + return -EINVAL; + + err = clk_prepare_enable(pc->clk); + if (err) + return err; + + duty_cycle = state->enabled ? state->duty_cycle : 0; + + err = pxa_pwm_config(chip, pwm, duty_cycle, state->period); + if (err) { + clk_disable_unprepare(pc->clk); + return err; + } + + if (state->enabled && !pwm->state.enabled) + return 0; + + clk_disable_unprepare(pc->clk); + + if (!state->enabled && pwm->state.enabled) + clk_disable_unprepare(pc->clk); + + return 0; +} + +static const struct pwm_ops pxa_pwm_ops = { + .apply = pxa_pwm_apply, + .owner = THIS_MODULE, +}; + +#ifdef CONFIG_OF +/* + * Device tree users must create one device instance for each PWM channel. + * Hence we dispense with the HAS_SECONDARY_PWM and "tell" the original driver + * code that this is a single channel pxa25x-pwm. Currently all devices are + * supported identically. + */ +static const struct of_device_id pwm_of_match[] = { + { .compatible = "marvell,pxa250-pwm", .data = &pwm_id_table[0]}, + { .compatible = "marvell,pxa270-pwm", .data = &pwm_id_table[0]}, + { .compatible = "marvell,pxa168-pwm", .data = &pwm_id_table[0]}, + { .compatible = "marvell,pxa910-pwm", .data = &pwm_id_table[0]}, + { } +}; +MODULE_DEVICE_TABLE(of, pwm_of_match); +#else +#define pwm_of_match NULL +#endif + +static int pwm_probe(struct platform_device *pdev) +{ + const struct platform_device_id *id = platform_get_device_id(pdev); + struct pxa_pwm_chip *pc; + int ret = 0; + + if (IS_ENABLED(CONFIG_OF) && id == NULL) + id = of_device_get_match_data(&pdev->dev); + + if (id == NULL) + return -EINVAL; + + pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL); + if (pc == NULL) + return -ENOMEM; + + pc->clk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(pc->clk)) + return PTR_ERR(pc->clk); + + pc->chip.dev = &pdev->dev; + pc->chip.ops = &pxa_pwm_ops; + pc->chip.npwm = (id->driver_data & HAS_SECONDARY_PWM) ? 2 : 1; + + if (IS_ENABLED(CONFIG_OF)) { + pc->chip.of_xlate = of_pwm_single_xlate; + pc->chip.of_pwm_n_cells = 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; + } + + return 0; +} + +static struct platform_driver pwm_driver = { + .driver = { + .name = "pxa25x-pwm", + .of_match_table = pwm_of_match, + }, + .probe = pwm_probe, + .id_table = pwm_id_table, +}; + +module_platform_driver(pwm_driver); + +MODULE_LICENSE("GPL v2"); |