diff options
Diffstat (limited to 'kernel/drivers/pwm/pwm-pxa.c')
| -rw-r--r-- | kernel/drivers/pwm/pwm-pxa.c | 237 |
1 files changed, 237 insertions, 0 deletions
diff --git a/kernel/drivers/pwm/pwm-pxa.c b/kernel/drivers/pwm/pwm-pxa.c new file mode 100644 index 000000000..cb2f7024c --- /dev/null +++ b/kernel/drivers/pwm/pwm-pxa.c @@ -0,0 +1,237 @@ +/* + * drivers/pwm/pwm-pxa.c + * + * simple driver for PWM (Pulse Width Modulator) controller + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * 2008-02-13 initial version + * eric miao <eric.miao@marvell.com> + */ + +#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, + int duty_ns, int 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; + int rc; + + 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 = (pv + 1) * duty_ns / period_ns; + + /* NOTE: the clock to PWM has to be enabled first + * before writing to the registers + */ + rc = clk_prepare_enable(pc->clk); + if (rc < 0) + return rc; + + writel(prescale, pc->mmio_base + offset + PWMCR); + writel(dc, pc->mmio_base + offset + PWMDCR); + writel(pv, pc->mmio_base + offset + PWMPCR); + + clk_disable_unprepare(pc->clk); + return 0; +} + +static int pxa_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) +{ + struct pxa_pwm_chip *pc = to_pxa_pwm_chip(chip); + + return clk_prepare_enable(pc->clk); +} + +static void pxa_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) +{ + struct pxa_pwm_chip *pc = to_pxa_pwm_chip(chip); + + clk_disable_unprepare(pc->clk); +} + +static struct pwm_ops pxa_pwm_ops = { + .config = pxa_pwm_config, + .enable = pxa_pwm_enable, + .disable = pxa_pwm_disable, + .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 const struct platform_device_id *pxa_pwm_get_id_dt(struct device *dev) +{ + const struct of_device_id *id = of_match_device(pwm_of_match, dev); + + return id ? id->data : NULL; +} + +static struct pwm_device * +pxa_pwm_of_xlate(struct pwm_chip *pc, const struct of_phandle_args *args) +{ + struct pwm_device *pwm; + + pwm = pwm_request_from_chip(pc, 0, NULL); + if (IS_ERR(pwm)) + return pwm; + + pwm_set_period(pwm, args->args[0]); + + return pwm; +} + +static int pwm_probe(struct platform_device *pdev) +{ + const struct platform_device_id *id = platform_get_device_id(pdev); + struct pxa_pwm_chip *pwm; + struct resource *r; + int ret = 0; + + if (IS_ENABLED(CONFIG_OF) && id == NULL) + id = pxa_pwm_get_id_dt(&pdev->dev); + + if (id == NULL) + return -EINVAL; + + pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL); + if (pwm == NULL) + return -ENOMEM; + + pwm->clk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(pwm->clk)) + return PTR_ERR(pwm->clk); + + pwm->chip.dev = &pdev->dev; + pwm->chip.ops = &pxa_pwm_ops; + pwm->chip.base = -1; + pwm->chip.npwm = (id->driver_data & HAS_SECONDARY_PWM) ? 2 : 1; + + if (IS_ENABLED(CONFIG_OF)) { + pwm->chip.of_xlate = pxa_pwm_of_xlate; + pwm->chip.of_pwm_n_cells = 1; + } + + r = platform_get_resource(pdev, IORESOURCE_MEM, 0); + pwm->mmio_base = devm_ioremap_resource(&pdev->dev, r); + if (IS_ERR(pwm->mmio_base)) + return PTR_ERR(pwm->mmio_base); + + ret = pwmchip_add(&pwm->chip); + if (ret < 0) { + dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret); + return ret; + } + + platform_set_drvdata(pdev, pwm); + return 0; +} + +static int pwm_remove(struct platform_device *pdev) +{ + struct pxa_pwm_chip *chip; + + chip = platform_get_drvdata(pdev); + if (chip == NULL) + return -ENODEV; + + return pwmchip_remove(&chip->chip); +} + +static struct platform_driver pwm_driver = { + .driver = { + .name = "pxa25x-pwm", + .of_match_table = pwm_of_match, + }, + .probe = pwm_probe, + .remove = pwm_remove, + .id_table = pwm_id_table, +}; + +module_platform_driver(pwm_driver); + +MODULE_LICENSE("GPL v2"); |