// 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. * - Each period starts with the inactive part. */ #include #include #include #include #include #include #include #include #include #define NUM_PWM 8 struct jz4740_pwm_chip { struct pwm_chip chip; }; static inline struct jz4740_pwm_chip *to_jz4740(struct pwm_chip *chip) { return container_of(chip, struct jz4740_pwm_chip, chip); } 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; /* * Timers 0 and 1 are used for system tasks, so they are unavailable * for use as PWMs. */ if (pwm->hwpwm < 2) return -EBUSY; snprintf(name, sizeof(name), "timer%u", pwm->hwpwm); clk = clk_get(chip->dev, name); if (IS_ERR(clk)) { if (PTR_ERR(clk) != -EPROBE_DEFER) dev_err(chip->dev, "Failed to get clock: %pe", 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) { uint32_t ctrl = jz4740_timer_get_ctrl(pwm->pwm); ctrl |= JZ_TIMER_CTRL_PWM_ENABLE; jz4740_timer_set_ctrl(pwm->hwpwm, ctrl); jz4740_timer_enable(pwm->hwpwm); return 0; } static void jz4740_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) { uint32_t ctrl = jz4740_timer_get_ctrl(pwm->hwpwm); /* * Set duty > period. This trick allows the TCU channels in TCU2 mode to * properly return to their init level. */ jz4740_timer_set_duty(pwm->hwpwm, 0xffff); jz4740_timer_set_period(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. */ ctrl &= ~JZ_TIMER_CTRL_PWM_ENABLE; jz4740_timer_set_ctrl(pwm->hwpwm, ctrl); /* Stop counter */ jz4740_timer_disable(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; uint16_t ctrl; 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 = (unsigned long)tmp; /* Calculate duty value */ tmp = (unsigned long long)period * state->duty_cycle; do_div(tmp, state->period); duty = period - 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; } jz4740_timer_set_count(pwm->hwpwm, 0); jz4740_timer_set_duty(pwm->hwpwm, duty); jz4740_timer_set_period(pwm->hwpwm, period); ctrl = jz4740_timer_get_ctrl(pwm->hwpwm); ctrl |= JZ_TIMER_CTRL_PWM_ABBRUPT_SHUTDOWN; switch (state->polarity) { case PWM_POLARITY_NORMAL: ctrl &= ~JZ_TIMER_CTRL_PWM_ACTIVE_LOW; break; case PWM_POLARITY_INVERSED: ctrl |= JZ_TIMER_CTRL_PWM_ACTIVE_LOW; break; } jz4740_timer_set_ctrl(pwm->hwpwm, ctrl); 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 jz4740_pwm_chip *jz4740; jz4740 = devm_kzalloc(&pdev->dev, sizeof(*jz4740), GFP_KERNEL); if (!jz4740) return -ENOMEM; jz4740->chip.dev = &pdev->dev; jz4740->chip.ops = &jz4740_pwm_ops; jz4740->chip.npwm = NUM_PWM; jz4740->chip.base = -1; jz4740->chip.of_xlate = of_pwm_xlate_with_flags; jz4740->chip.of_pwm_n_cells = 3; platform_set_drvdata(pdev, jz4740); return pwmchip_add(&jz4740->chip); } static int jz4740_pwm_remove(struct platform_device *pdev) { struct jz4740_pwm_chip *jz4740 = platform_get_drvdata(pdev); return pwmchip_remove(&jz4740->chip); } #ifdef CONFIG_OF static const struct of_device_id jz4740_pwm_dt_ids[] = { { .compatible = "ingenic,jz4740-pwm", }, {}, }; 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, .remove = jz4740_pwm_remove, }; 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");