1 // SPDX-License-Identifier: GPL-2.0-only
8  * enough to be briefly explained. It consists of one 8-bit counter. The PWM
15  * +-----------+--------+--------------+-----------+---------------+
17  * +-----------+--------+--------------+-----------+---------------+
22  * +-----------+--------+--------------+-----------+---------------+
25  * - The hardware cannot generate a 100% duty cycle if the prescaler is 0.
26  * - The hardware cannot atomically set the prescaler and the counter value,
28  * - The counter is not reset if you switch the prescaler which leads
30  * - The duty cycle will switch immediately and not after a complete cycle.
31  * - Depending on the actual implementation, disabling the PWM might have
55 #define SL28CPLD_PWM_MAX_DUTY_CYCLE(prescaler)	(1 << (7 - (prescaler)))
60  * We calculate the duty cycle like this:
64  *   max_period_ns = 1 << (7 - prescaler) / SL28CPLD_PWM_CLK * NSEC_PER_SEC
65  *   max_duty_cycle = 1 << (7 - prescaler)
79 	regmap_read((priv)->regmap, (priv)->offset + (reg), (val))
81 	regmap_write((priv)->regmap, (priv)->offset + (reg), (val))
104 	state->enabled = reg & SL28CPLD_PWM_CTRL_ENABLE;  in sl28cpld_pwm_get_state()
107 	state->period = SL28CPLD_PWM_PERIOD(prescaler);  in sl28cpld_pwm_get_state()
110 	state->duty_cycle = SL28CPLD_PWM_TO_DUTY_CYCLE(reg);  in sl28cpld_pwm_get_state()
111 	state->polarity = PWM_POLARITY_NORMAL;  in sl28cpld_pwm_get_state()
121 	state->duty_cycle = min(state->duty_cycle, state->period);  in sl28cpld_pwm_get_state()
130 	unsigned int cycle, prescaler;  in sl28cpld_pwm_apply()  local
136 	if (state->polarity != PWM_POLARITY_NORMAL)  in sl28cpld_pwm_apply()
137 		return -EINVAL;  in sl28cpld_pwm_apply()
143 	prescaler = DIV_ROUND_UP_ULL(SL28CPLD_PWM_PERIOD(0), state->period);  in sl28cpld_pwm_apply()
147 		return -ERANGE;  in sl28cpld_pwm_apply()
150 	if (state->enabled)  in sl28cpld_pwm_apply()
153 	cycle = SL28CPLD_PWM_FROM_DUTY_CYCLE(state->duty_cycle);  in sl28cpld_pwm_apply()
154 	cycle = min_t(unsigned int, cycle, SL28CPLD_PWM_MAX_DUTY_CYCLE(prescaler));  in sl28cpld_pwm_apply()
157 	 * Work around the hardware limitation. See also above. Trap 100% duty  in sl28cpld_pwm_apply()
158 	 * cycle if the prescaler is 0. Set prescaler to 1 instead. We don't  in sl28cpld_pwm_apply()
159 	 * care about the frequency because its "all-one" in either case.  in sl28cpld_pwm_apply()
164 	if (cycle == SL28CPLD_PWM_MAX_DUTY_CYCLE(0)) {  in sl28cpld_pwm_apply()
167 		cycle = SL28CPLD_PWM_MAX_DUTY_CYCLE(1);  in sl28cpld_pwm_apply()
172 	 * we have a valid duty cycle for the new mode.  in sl28cpld_pwm_apply()
175 	 * account to decide whether we have to write the duty cycle or the new  in sl28cpld_pwm_apply()
177 	 * write the duty cycle first.  in sl28cpld_pwm_apply()
179 	write_duty_cycle_first = pwm->state.period > state->period;  in sl28cpld_pwm_apply()
182 		ret = sl28cpld_pwm_write(priv, SL28CPLD_PWM_CYCLE, cycle);  in sl28cpld_pwm_apply()
192 		ret = sl28cpld_pwm_write(priv, SL28CPLD_PWM_CYCLE, cycle);  in sl28cpld_pwm_apply()
212 	if (!pdev->dev.parent) {  in sl28cpld_pwm_probe()
213 		dev_err(&pdev->dev, "no parent device\n");  in sl28cpld_pwm_probe()
214 		return -ENODEV;  in sl28cpld_pwm_probe()
217 	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);  in sl28cpld_pwm_probe()
219 		return -ENOMEM;  in sl28cpld_pwm_probe()
221 	priv->regmap = dev_get_regmap(pdev->dev.parent, NULL);  in sl28cpld_pwm_probe()
222 	if (!priv->regmap) {  in sl28cpld_pwm_probe()
223 		dev_err(&pdev->dev, "could not get parent regmap\n");  in sl28cpld_pwm_probe()
224 		return -ENODEV;  in sl28cpld_pwm_probe()
227 	ret = device_property_read_u32(&pdev->dev, "reg", &priv->offset);  in sl28cpld_pwm_probe()
229 		dev_err(&pdev->dev, "no 'reg' property found (%pe)\n",  in sl28cpld_pwm_probe()
231 		return -EINVAL;  in sl28cpld_pwm_probe()
235 	chip = &priv->chip;  in sl28cpld_pwm_probe()
236 	chip->dev = &pdev->dev;  in sl28cpld_pwm_probe()
237 	chip->ops = &sl28cpld_pwm_ops;  in sl28cpld_pwm_probe()
238 	chip->npwm = 1;  in sl28cpld_pwm_probe()
240 	ret = devm_pwmchip_add(&pdev->dev, chip);  in sl28cpld_pwm_probe()
242 		dev_err(&pdev->dev, "failed to add PWM chip (%pe)",  in sl28cpld_pwm_probe()
251 	{ .compatible = "kontron,sl28cpld-pwm" },
259 		.name = "sl28cpld-pwm",