// SPDX-License-Identifier: GPL-2.0-or-later /* * Copyright (C) 2010, Lars-Peter Clausen * JZ4740 platform PWM support * * Limitations: * - The .apply callback doesn't complete the currently running period before * reconfiguring the hardware. */ #include #include #include #include #include #include #include #include #include #include #include struct soc_info { unsigned int num_pwms; }; struct jz4740_pwm_chip { struct pwm_chip chip; struct regmap *map; }; static inline struct jz4740_pwm_chip *to_jz4740(struct pwm_chip *chip) { return container_of(chip, struct jz4740_pwm_chip, chip); } static bool jz4740_pwm_can_use_chn(struct jz4740_pwm_chip *jz, unsigned int channel) { /* Enable all TCU channels for PWM use by default except channels 0/1 */ u32 pwm_channels_mask = GENMASK(jz->chip.npwm - 1, 2); device_property_read_u32(jz->chip.dev->parent, "ingenic,pwm-channels-mask", &pwm_channels_mask); return !!(pwm_channels_mask & BIT(channel)); } static int jz4740_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm) { struct jz4740_pwm_chip *jz = to_jz4740(chip); struct clk *clk; char name[16]; int err; if (!jz4740_pwm_can_use_chn(jz, pwm->hwpwm)) return -EBUSY; snprintf(name, sizeof(name), "timer%u", pwm->hwpwm); clk = clk_get(chip->dev, name); if (IS_ERR(clk)) { dev_err(chip->dev, "error %pe: Failed to get clock\n", clk); return PTR_ERR(clk); } err = clk_prepare_enable(clk); if (err < 0) { clk_put(clk); return err; } pwm_set_chip_data(pwm, clk); return 0; } static void jz4740_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm) { struct clk *clk = pwm_get_chip_data(pwm); clk_disable_unprepare(clk); clk_put(clk); } static int jz4740_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) { struct jz4740_pwm_chip *jz = to_jz4740(chip); /* Enable PWM output */ regmap_update_bits(jz->map, TCU_REG_TCSRc(pwm->hwpwm), TCU_TCSR_PWM_EN, TCU_TCSR_PWM_EN); /* Start counter */ regmap_write(jz->map, TCU_REG_TESR, BIT(pwm->hwpwm)); return 0; } static void jz4740_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) { struct jz4740_pwm_chip *jz = to_jz4740(chip); /* * Set duty > period. This trick allows the TCU channels in TCU2 mode to * properly return to their init level. */ regmap_write(jz->map, TCU_REG_TDHRc(pwm->hwpwm), 0xffff); regmap_write(jz->map, TCU_REG_TDFRc(pwm->hwpwm), 0x0); /* * Disable PWM output. * In TCU2 mode (channel 1/2 on JZ4750+), this must be done before the * counter is stopped, while in TCU1 mode the order does not matter. */ regmap_update_bits(jz->map, TCU_REG_TCSRc(pwm->hwpwm), TCU_TCSR_PWM_EN, 0); /* Stop counter */ regmap_write(jz->map, TCU_REG_TECR, BIT(pwm->hwpwm)); } static int jz4740_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, const struct pwm_state *state) { struct jz4740_pwm_chip *jz4740 = to_jz4740(pwm->chip); unsigned long long tmp = 0xffffull * NSEC_PER_SEC; struct clk *clk = pwm_get_chip_data(pwm); unsigned long period, duty; long rate; int err; /* * Limit the clock to a maximum rate that still gives us a period value * which fits in 16 bits. */ do_div(tmp, state->period); /* * /!\ IMPORTANT NOTE: * ------------------- * This code relies on the fact that clk_round_rate() will always round * down, which is not a valid assumption given by the clk API, but only * happens to be true with the clk drivers used for Ingenic SoCs. * * Right now, there is no alternative as the clk API does not have a * round-down function (and won't have one for a while), but if it ever * comes to light, a round-down function should be used instead. */ rate = clk_round_rate(clk, tmp); if (rate < 0) { dev_err(chip->dev, "Unable to round rate: %ld", rate); return rate; } /* Calculate period value */ tmp = (unsigned long long)rate * state->period; do_div(tmp, NSEC_PER_SEC); period = tmp; /* Calculate duty value */ tmp = (unsigned long long)rate * state->duty_cycle; do_div(tmp, NSEC_PER_SEC); duty = tmp; if (duty >= period) duty = period - 1; jz4740_pwm_disable(chip, pwm); err = clk_set_rate(clk, rate); if (err) { dev_err(chip->dev, "Unable to set rate: %d", err); return err; } /* Reset counter to 0 */ regmap_write(jz4740->map, TCU_REG_TCNTc(pwm->hwpwm), 0); /* Set duty */ regmap_write(jz4740->map, TCU_REG_TDHRc(pwm->hwpwm), duty); /* Set period */ regmap_write(jz4740->map, TCU_REG_TDFRc(pwm->hwpwm), period); /* Set abrupt shutdown */ regmap_update_bits(jz4740->map, TCU_REG_TCSRc(pwm->hwpwm), TCU_TCSR_PWM_SD, TCU_TCSR_PWM_SD); /* * Set polarity. * * The PWM starts in inactive state until the internal timer reaches the * duty value, then becomes active until the timer reaches the period * value. In theory, we should then use (period - duty) as the real duty * value, as a high duty value would otherwise result in the PWM pin * being inactive most of the time. * * Here, we don't do that, and instead invert the polarity of the PWM * when it is active. This trick makes the PWM start with its active * state instead of its inactive state. */ if ((state->polarity == PWM_POLARITY_NORMAL) ^ state->enabled) regmap_update_bits(jz4740->map, TCU_REG_TCSRc(pwm->hwpwm), TCU_TCSR_PWM_INITL_HIGH, 0); else regmap_update_bits(jz4740->map, TCU_REG_TCSRc(pwm->hwpwm), TCU_TCSR_PWM_INITL_HIGH, TCU_TCSR_PWM_INITL_HIGH); if (state->enabled) jz4740_pwm_enable(chip, pwm); return 0; } static const struct pwm_ops jz4740_pwm_ops = { .request = jz4740_pwm_request, .free = jz4740_pwm_free, .apply = jz4740_pwm_apply, .owner = THIS_MODULE, }; static int jz4740_pwm_probe(struct platform_device *pdev) { struct device *dev = &pdev->dev; struct jz4740_pwm_chip *jz4740; const struct soc_info *info; info = device_get_match_data(dev); if (!info) return -EINVAL; jz4740 = devm_kzalloc(dev, sizeof(*jz4740), GFP_KERNEL); if (!jz4740) return -ENOMEM; jz4740->map = device_node_to_regmap(dev->parent->of_node); if (IS_ERR(jz4740->map)) { dev_err(dev, "regmap not found: %ld\n", PTR_ERR(jz4740->map)); return PTR_ERR(jz4740->map); } jz4740->chip.dev = dev; jz4740->chip.ops = &jz4740_pwm_ops; jz4740->chip.npwm = info->num_pwms; return devm_pwmchip_add(dev, &jz4740->chip); } static const struct soc_info __maybe_unused jz4740_soc_info = { .num_pwms = 8, }; static const struct soc_info __maybe_unused jz4725b_soc_info = { .num_pwms = 6, }; #ifdef CONFIG_OF static const struct of_device_id jz4740_pwm_dt_ids[] = { { .compatible = "ingenic,jz4740-pwm", .data = &jz4740_soc_info }, { .compatible = "ingenic,jz4725b-pwm", .data = &jz4725b_soc_info }, {}, }; MODULE_DEVICE_TABLE(of, jz4740_pwm_dt_ids); #endif static struct platform_driver jz4740_pwm_driver = { .driver = { .name = "jz4740-pwm", .of_match_table = of_match_ptr(jz4740_pwm_dt_ids), }, .probe = jz4740_pwm_probe, }; module_platform_driver(jz4740_pwm_driver); MODULE_AUTHOR("Lars-Peter Clausen "); MODULE_DESCRIPTION("Ingenic JZ4740 PWM driver"); MODULE_ALIAS("platform:jz4740-pwm"); MODULE_LICENSE("GPL");