diff options
Diffstat (limited to 'drivers/pwm/pwm-imx-tpm.c')
| -rw-r--r-- | drivers/pwm/pwm-imx-tpm.c | 448 |
1 files changed, 448 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-imx-tpm.c b/drivers/pwm/pwm-imx-tpm.c new file mode 100644 index 000000000..318dc0be9 --- /dev/null +++ b/drivers/pwm/pwm-imx-tpm.c @@ -0,0 +1,448 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright 2018-2019 NXP. + * + * Limitations: + * - The TPM counter and period counter are shared between + * multiple channels, so all channels should use same period + * settings. + * - Changes to polarity cannot be latched at the time of the + * next period start. + * - Changing period and duty cycle together isn't atomic, + * with the wrong timing it might happen that a period is + * produced with old duty cycle but new period settings. + */ + +#include <linux/bitfield.h> +#include <linux/bitops.h> +#include <linux/clk.h> +#include <linux/err.h> +#include <linux/io.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/platform_device.h> +#include <linux/pwm.h> +#include <linux/slab.h> + +#define PWM_IMX_TPM_PARAM 0x4 +#define PWM_IMX_TPM_GLOBAL 0x8 +#define PWM_IMX_TPM_SC 0x10 +#define PWM_IMX_TPM_CNT 0x14 +#define PWM_IMX_TPM_MOD 0x18 +#define PWM_IMX_TPM_CnSC(n) (0x20 + (n) * 0x8) +#define PWM_IMX_TPM_CnV(n) (0x24 + (n) * 0x8) + +#define PWM_IMX_TPM_PARAM_CHAN GENMASK(7, 0) + +#define PWM_IMX_TPM_SC_PS GENMASK(2, 0) +#define PWM_IMX_TPM_SC_CMOD GENMASK(4, 3) +#define PWM_IMX_TPM_SC_CMOD_INC_EVERY_CLK FIELD_PREP(PWM_IMX_TPM_SC_CMOD, 1) +#define PWM_IMX_TPM_SC_CPWMS BIT(5) + +#define PWM_IMX_TPM_CnSC_CHF BIT(7) +#define PWM_IMX_TPM_CnSC_MSB BIT(5) +#define PWM_IMX_TPM_CnSC_MSA BIT(4) + +/* + * The reference manual describes this field as two separate bits. The + * semantic of the two bits isn't orthogonal though, so they are treated + * together as a 2-bit field here. + */ +#define PWM_IMX_TPM_CnSC_ELS GENMASK(3, 2) +#define PWM_IMX_TPM_CnSC_ELS_INVERSED FIELD_PREP(PWM_IMX_TPM_CnSC_ELS, 1) +#define PWM_IMX_TPM_CnSC_ELS_NORMAL FIELD_PREP(PWM_IMX_TPM_CnSC_ELS, 2) + + +#define PWM_IMX_TPM_MOD_WIDTH 16 +#define PWM_IMX_TPM_MOD_MOD GENMASK(PWM_IMX_TPM_MOD_WIDTH - 1, 0) + +struct imx_tpm_pwm_chip { + struct pwm_chip chip; + struct clk *clk; + void __iomem *base; + struct mutex lock; + u32 user_count; + u32 enable_count; + u32 real_period; +}; + +struct imx_tpm_pwm_param { + u8 prescale; + u32 mod; + u32 val; +}; + +static inline struct imx_tpm_pwm_chip * +to_imx_tpm_pwm_chip(struct pwm_chip *chip) +{ + return container_of(chip, struct imx_tpm_pwm_chip, chip); +} + +/* + * This function determines for a given pwm_state *state that a consumer + * might request the pwm_state *real_state that eventually is implemented + * by the hardware and the necessary register values (in *p) to achieve + * this. + */ +static int pwm_imx_tpm_round_state(struct pwm_chip *chip, + struct imx_tpm_pwm_param *p, + struct pwm_state *real_state, + const struct pwm_state *state) +{ + struct imx_tpm_pwm_chip *tpm = to_imx_tpm_pwm_chip(chip); + u32 rate, prescale, period_count, clock_unit; + u64 tmp; + + rate = clk_get_rate(tpm->clk); + tmp = (u64)state->period * rate; + clock_unit = DIV_ROUND_CLOSEST_ULL(tmp, NSEC_PER_SEC); + if (clock_unit <= PWM_IMX_TPM_MOD_MOD) + prescale = 0; + else + prescale = ilog2(clock_unit) + 1 - PWM_IMX_TPM_MOD_WIDTH; + + if ((!FIELD_FIT(PWM_IMX_TPM_SC_PS, prescale))) + return -ERANGE; + p->prescale = prescale; + + period_count = (clock_unit + ((1 << prescale) >> 1)) >> prescale; + p->mod = period_count; + + /* calculate real period HW can support */ + tmp = (u64)period_count << prescale; + tmp *= NSEC_PER_SEC; + real_state->period = DIV_ROUND_CLOSEST_ULL(tmp, rate); + + /* + * if eventually the PWM output is inactive, either + * duty cycle is 0 or status is disabled, need to + * make sure the output pin is inactive. + */ + if (!state->enabled) + real_state->duty_cycle = 0; + else + real_state->duty_cycle = state->duty_cycle; + + tmp = (u64)p->mod * real_state->duty_cycle; + p->val = DIV64_U64_ROUND_CLOSEST(tmp, real_state->period); + + real_state->polarity = state->polarity; + real_state->enabled = state->enabled; + + return 0; +} + +static int pwm_imx_tpm_get_state(struct pwm_chip *chip, + struct pwm_device *pwm, + struct pwm_state *state) +{ + struct imx_tpm_pwm_chip *tpm = to_imx_tpm_pwm_chip(chip); + u32 rate, val, prescale; + u64 tmp; + + /* get period */ + state->period = tpm->real_period; + + /* get duty cycle */ + rate = clk_get_rate(tpm->clk); + val = readl(tpm->base + PWM_IMX_TPM_SC); + prescale = FIELD_GET(PWM_IMX_TPM_SC_PS, val); + tmp = readl(tpm->base + PWM_IMX_TPM_CnV(pwm->hwpwm)); + tmp = (tmp << prescale) * NSEC_PER_SEC; + state->duty_cycle = DIV_ROUND_CLOSEST_ULL(tmp, rate); + + /* get polarity */ + val = readl(tpm->base + PWM_IMX_TPM_CnSC(pwm->hwpwm)); + if ((val & PWM_IMX_TPM_CnSC_ELS) == PWM_IMX_TPM_CnSC_ELS_INVERSED) + state->polarity = PWM_POLARITY_INVERSED; + else + /* + * Assume reserved values (2b00 and 2b11) to yield + * normal polarity. + */ + state->polarity = PWM_POLARITY_NORMAL; + + /* get channel status */ + state->enabled = FIELD_GET(PWM_IMX_TPM_CnSC_ELS, val) ? true : false; + + return 0; +} + +/* this function is supposed to be called with mutex hold */ +static int pwm_imx_tpm_apply_hw(struct pwm_chip *chip, + struct imx_tpm_pwm_param *p, + struct pwm_state *state, + struct pwm_device *pwm) +{ + struct imx_tpm_pwm_chip *tpm = to_imx_tpm_pwm_chip(chip); + bool period_update = false; + bool duty_update = false; + u32 val, cmod, cur_prescale; + unsigned long timeout; + struct pwm_state c; + + if (state->period != tpm->real_period) { + /* + * TPM counter is shared by multiple channels, so + * prescale and period can NOT be modified when + * there are multiple channels in use with different + * period settings. + */ + if (tpm->user_count > 1) + return -EBUSY; + + val = readl(tpm->base + PWM_IMX_TPM_SC); + cmod = FIELD_GET(PWM_IMX_TPM_SC_CMOD, val); + cur_prescale = FIELD_GET(PWM_IMX_TPM_SC_PS, val); + if (cmod && cur_prescale != p->prescale) + return -EBUSY; + + /* set TPM counter prescale */ + val &= ~PWM_IMX_TPM_SC_PS; + val |= FIELD_PREP(PWM_IMX_TPM_SC_PS, p->prescale); + writel(val, tpm->base + PWM_IMX_TPM_SC); + + /* + * set period count: + * if the PWM is disabled (CMOD[1:0] = 2b00), then MOD register + * is updated when MOD register is written. + * + * if the PWM is enabled (CMOD[1:0] ≠ 2b00), the period length + * is latched into hardware when the next period starts. + */ + writel(p->mod, tpm->base + PWM_IMX_TPM_MOD); + tpm->real_period = state->period; + period_update = true; + } + + pwm_imx_tpm_get_state(chip, pwm, &c); + + /* polarity is NOT allowed to be changed if PWM is active */ + if (c.enabled && c.polarity != state->polarity) + return -EBUSY; + + if (state->duty_cycle != c.duty_cycle) { + /* + * set channel value: + * if the PWM is disabled (CMOD[1:0] = 2b00), then CnV register + * is updated when CnV register is written. + * + * if the PWM is enabled (CMOD[1:0] ≠ 2b00), the duty length + * is latched into hardware when the next period starts. + */ + writel(p->val, tpm->base + PWM_IMX_TPM_CnV(pwm->hwpwm)); + duty_update = true; + } + + /* make sure MOD & CnV registers are updated */ + if (period_update || duty_update) { + timeout = jiffies + msecs_to_jiffies(tpm->real_period / + NSEC_PER_MSEC + 1); + while (readl(tpm->base + PWM_IMX_TPM_MOD) != p->mod + || readl(tpm->base + PWM_IMX_TPM_CnV(pwm->hwpwm)) + != p->val) { + if (time_after(jiffies, timeout)) + return -ETIME; + cpu_relax(); + } + } + + /* + * polarity settings will enabled/disable output status + * immediately, so if the channel is disabled, need to + * make sure MSA/MSB/ELS are set to 0 which means channel + * disabled. + */ + val = readl(tpm->base + PWM_IMX_TPM_CnSC(pwm->hwpwm)); + val &= ~(PWM_IMX_TPM_CnSC_ELS | PWM_IMX_TPM_CnSC_MSA | + PWM_IMX_TPM_CnSC_MSB); + if (state->enabled) { + /* + * set polarity (for edge-aligned PWM modes) + * + * ELS[1:0] = 2b10 yields normal polarity behaviour, + * ELS[1:0] = 2b01 yields inversed polarity. + * The other values are reserved. + */ + val |= PWM_IMX_TPM_CnSC_MSB; + val |= (state->polarity == PWM_POLARITY_NORMAL) ? + PWM_IMX_TPM_CnSC_ELS_NORMAL : + PWM_IMX_TPM_CnSC_ELS_INVERSED; + } + writel(val, tpm->base + PWM_IMX_TPM_CnSC(pwm->hwpwm)); + + /* control the counter status */ + if (state->enabled != c.enabled) { + val = readl(tpm->base + PWM_IMX_TPM_SC); + if (state->enabled) { + if (++tpm->enable_count == 1) + val |= PWM_IMX_TPM_SC_CMOD_INC_EVERY_CLK; + } else { + if (--tpm->enable_count == 0) + val &= ~PWM_IMX_TPM_SC_CMOD; + } + writel(val, tpm->base + PWM_IMX_TPM_SC); + } + + return 0; +} + +static int pwm_imx_tpm_apply(struct pwm_chip *chip, + struct pwm_device *pwm, + const struct pwm_state *state) +{ + struct imx_tpm_pwm_chip *tpm = to_imx_tpm_pwm_chip(chip); + struct imx_tpm_pwm_param param; + struct pwm_state real_state; + int ret; + + ret = pwm_imx_tpm_round_state(chip, ¶m, &real_state, state); + if (ret) + return ret; + + mutex_lock(&tpm->lock); + ret = pwm_imx_tpm_apply_hw(chip, ¶m, &real_state, pwm); + mutex_unlock(&tpm->lock); + + return ret; +} + +static int pwm_imx_tpm_request(struct pwm_chip *chip, struct pwm_device *pwm) +{ + struct imx_tpm_pwm_chip *tpm = to_imx_tpm_pwm_chip(chip); + + mutex_lock(&tpm->lock); + tpm->user_count++; + mutex_unlock(&tpm->lock); + + return 0; +} + +static void pwm_imx_tpm_free(struct pwm_chip *chip, struct pwm_device *pwm) +{ + struct imx_tpm_pwm_chip *tpm = to_imx_tpm_pwm_chip(chip); + + mutex_lock(&tpm->lock); + tpm->user_count--; + mutex_unlock(&tpm->lock); +} + +static const struct pwm_ops imx_tpm_pwm_ops = { + .request = pwm_imx_tpm_request, + .free = pwm_imx_tpm_free, + .get_state = pwm_imx_tpm_get_state, + .apply = pwm_imx_tpm_apply, + .owner = THIS_MODULE, +}; + +static int pwm_imx_tpm_probe(struct platform_device *pdev) +{ + struct imx_tpm_pwm_chip *tpm; + int ret; + u32 val; + + tpm = devm_kzalloc(&pdev->dev, sizeof(*tpm), GFP_KERNEL); + if (!tpm) + return -ENOMEM; + + platform_set_drvdata(pdev, tpm); + + tpm->base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(tpm->base)) + return PTR_ERR(tpm->base); + + tpm->clk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(tpm->clk)) + return dev_err_probe(&pdev->dev, PTR_ERR(tpm->clk), + "failed to get PWM clock\n"); + + ret = clk_prepare_enable(tpm->clk); + if (ret) { + dev_err(&pdev->dev, + "failed to prepare or enable clock: %d\n", ret); + return ret; + } + + tpm->chip.dev = &pdev->dev; + tpm->chip.ops = &imx_tpm_pwm_ops; + + /* get number of channels */ + val = readl(tpm->base + PWM_IMX_TPM_PARAM); + tpm->chip.npwm = FIELD_GET(PWM_IMX_TPM_PARAM_CHAN, val); + + mutex_init(&tpm->lock); + + ret = pwmchip_add(&tpm->chip); + if (ret) { + dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret); + clk_disable_unprepare(tpm->clk); + } + + return ret; +} + +static int pwm_imx_tpm_remove(struct platform_device *pdev) +{ + struct imx_tpm_pwm_chip *tpm = platform_get_drvdata(pdev); + + pwmchip_remove(&tpm->chip); + + clk_disable_unprepare(tpm->clk); + + return 0; +} + +static int __maybe_unused pwm_imx_tpm_suspend(struct device *dev) +{ + struct imx_tpm_pwm_chip *tpm = dev_get_drvdata(dev); + + if (tpm->enable_count > 0) + return -EBUSY; + + /* + * Force 'real_period' to be zero to force period update code + * can be executed after system resume back, since suspend causes + * the period related registers to become their reset values. + */ + tpm->real_period = 0; + + clk_disable_unprepare(tpm->clk); + + return 0; +} + +static int __maybe_unused pwm_imx_tpm_resume(struct device *dev) +{ + struct imx_tpm_pwm_chip *tpm = dev_get_drvdata(dev); + int ret = 0; + + ret = clk_prepare_enable(tpm->clk); + if (ret) + dev_err(dev, "failed to prepare or enable clock: %d\n", ret); + + return ret; +} + +static SIMPLE_DEV_PM_OPS(imx_tpm_pwm_pm, + pwm_imx_tpm_suspend, pwm_imx_tpm_resume); + +static const struct of_device_id imx_tpm_pwm_dt_ids[] = { + { .compatible = "fsl,imx7ulp-pwm", }, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(of, imx_tpm_pwm_dt_ids); + +static struct platform_driver imx_tpm_pwm_driver = { + .driver = { + .name = "imx7ulp-tpm-pwm", + .of_match_table = imx_tpm_pwm_dt_ids, + .pm = &imx_tpm_pwm_pm, + }, + .probe = pwm_imx_tpm_probe, + .remove = pwm_imx_tpm_remove, +}; +module_platform_driver(imx_tpm_pwm_driver); + +MODULE_AUTHOR("Anson Huang <Anson.Huang@nxp.com>"); +MODULE_DESCRIPTION("i.MX TPM PWM Driver"); +MODULE_LICENSE("GPL v2"); |