diff options
Diffstat (limited to '')
| -rw-r--r-- | drivers/pwm/pwm-mxs.c | 180 |
1 files changed, 180 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-mxs.c b/drivers/pwm/pwm-mxs.c new file mode 100644 index 000000000..766dbc58d --- /dev/null +++ b/drivers/pwm/pwm-mxs.c @@ -0,0 +1,180 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Copyright 2012 Freescale Semiconductor, Inc. + */ + +#include <linux/clk.h> +#include <linux/err.h> +#include <linux/io.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/platform_device.h> +#include <linux/pwm.h> +#include <linux/slab.h> +#include <linux/stmp_device.h> + +#define SET 0x4 +#define CLR 0x8 +#define TOG 0xc + +#define PWM_CTRL 0x0 +#define PWM_ACTIVE0 0x10 +#define PWM_PERIOD0 0x20 +#define PERIOD_PERIOD(p) ((p) & 0xffff) +#define PERIOD_PERIOD_MAX 0x10000 +#define PERIOD_ACTIVE_HIGH (3 << 16) +#define PERIOD_ACTIVE_LOW (2 << 16) +#define PERIOD_INACTIVE_HIGH (3 << 18) +#define PERIOD_INACTIVE_LOW (2 << 18) +#define PERIOD_POLARITY_NORMAL (PERIOD_ACTIVE_HIGH | PERIOD_INACTIVE_LOW) +#define PERIOD_POLARITY_INVERSE (PERIOD_ACTIVE_LOW | PERIOD_INACTIVE_HIGH) +#define PERIOD_CDIV(div) (((div) & 0x7) << 20) +#define PERIOD_CDIV_MAX 8 + +static const u8 cdiv_shift[PERIOD_CDIV_MAX] = { + 0, 1, 2, 3, 4, 6, 8, 10 +}; + +struct mxs_pwm_chip { + struct pwm_chip chip; + struct clk *clk; + void __iomem *base; +}; + +#define to_mxs_pwm_chip(_chip) container_of(_chip, struct mxs_pwm_chip, chip) + +static int mxs_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, + const struct pwm_state *state) +{ + struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip); + int ret, div = 0; + unsigned int period_cycles, duty_cycles; + unsigned long rate; + unsigned long long c; + unsigned int pol_bits; + + /* + * If the PWM channel is disabled, make sure to turn on the + * clock before calling clk_get_rate() and writing to the + * registers. Otherwise, just keep it enabled. + */ + if (!pwm_is_enabled(pwm)) { + ret = clk_prepare_enable(mxs->clk); + if (ret) + return ret; + } + + if (!state->enabled && pwm_is_enabled(pwm)) + writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + CLR); + + rate = clk_get_rate(mxs->clk); + while (1) { + c = rate >> cdiv_shift[div]; + c = c * state->period; + do_div(c, 1000000000); + if (c < PERIOD_PERIOD_MAX) + break; + div++; + if (div >= PERIOD_CDIV_MAX) + return -EINVAL; + } + + period_cycles = c; + c *= state->duty_cycle; + do_div(c, state->period); + duty_cycles = c; + + /* + * The data sheet the says registers must be written to in + * this order (ACTIVEn, then PERIODn). Also, the new settings + * only take effect at the beginning of a new period, avoiding + * glitches. + */ + + pol_bits = state->polarity == PWM_POLARITY_NORMAL ? + PERIOD_POLARITY_NORMAL : PERIOD_POLARITY_INVERSE; + writel(duty_cycles << 16, + mxs->base + PWM_ACTIVE0 + pwm->hwpwm * 0x20); + writel(PERIOD_PERIOD(period_cycles) | pol_bits | PERIOD_CDIV(div), + mxs->base + PWM_PERIOD0 + pwm->hwpwm * 0x20); + + if (state->enabled) { + if (!pwm_is_enabled(pwm)) { + /* + * The clock was enabled above. Just enable + * the channel in the control register. + */ + writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + SET); + } + } else { + clk_disable_unprepare(mxs->clk); + } + return 0; +} + +static const struct pwm_ops mxs_pwm_ops = { + .apply = mxs_pwm_apply, + .owner = THIS_MODULE, +}; + +static int mxs_pwm_probe(struct platform_device *pdev) +{ + struct device_node *np = pdev->dev.of_node; + struct mxs_pwm_chip *mxs; + int ret; + + mxs = devm_kzalloc(&pdev->dev, sizeof(*mxs), GFP_KERNEL); + if (!mxs) + return -ENOMEM; + + mxs->base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(mxs->base)) + return PTR_ERR(mxs->base); + + mxs->clk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(mxs->clk)) + return PTR_ERR(mxs->clk); + + mxs->chip.dev = &pdev->dev; + mxs->chip.ops = &mxs_pwm_ops; + + ret = of_property_read_u32(np, "fsl,pwm-number", &mxs->chip.npwm); + if (ret < 0) { + dev_err(&pdev->dev, "failed to get pwm number: %d\n", ret); + return ret; + } + + /* FIXME: Only do this if the PWM isn't already running */ + ret = stmp_reset_block(mxs->base); + if (ret) + return dev_err_probe(&pdev->dev, ret, "failed to reset PWM\n"); + + ret = devm_pwmchip_add(&pdev->dev, &mxs->chip); + if (ret < 0) { + dev_err(&pdev->dev, "failed to add pwm chip %d\n", ret); + return ret; + } + + return 0; +} + +static const struct of_device_id mxs_pwm_dt_ids[] = { + { .compatible = "fsl,imx23-pwm", }, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(of, mxs_pwm_dt_ids); + +static struct platform_driver mxs_pwm_driver = { + .driver = { + .name = "mxs-pwm", + .of_match_table = mxs_pwm_dt_ids, + }, + .probe = mxs_pwm_probe, +}; +module_platform_driver(mxs_pwm_driver); + +MODULE_ALIAS("platform:mxs-pwm"); +MODULE_AUTHOR("Shawn Guo <shawn.guo@linaro.org>"); +MODULE_DESCRIPTION("Freescale MXS PWM Driver"); +MODULE_LICENSE("GPL v2"); |