--- /dev/null
+// 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/log2.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.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,
+ 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 = DIV_ROUND_CLOSEST_ULL(tmp, real_state->period);
+
+ real_state->polarity = state->polarity;
+ real_state->enabled = state->enabled;
+
+ return 0;
+}
+
+static void 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;
+}
+
+/* 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,
+ 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)) {
+ ret = PTR_ERR(tpm->clk);
+ if (ret != -EPROBE_DEFER)
+ dev_err(&pdev->dev,
+ "failed to get PWM clock: %d\n", ret);
+ return ret;
+ }
+
+ 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;
+ tpm->chip.base = -1;
+ tpm->chip.of_xlate = of_pwm_xlate_with_flags;
+ tpm->chip.of_pwm_n_cells = 3;
+
+ /* 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);
+ int ret = pwmchip_remove(&tpm->chip);
+
+ clk_disable_unprepare(tpm->clk);
+
+ return ret;
+}
+
+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;
+
+ 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");
OSDN Git Service
