1 // SPDX-License-Identifier: GPL-2.0-or-later
4  * e-book readers designed by the original design manufacturer Netronix, Inc.
5  * It contains RTC, battery monitoring, system power management, and PWM
8  * This driver implements PWM output.
13  * - The get_state callback is not implemented, because the current state of
14  *   the PWM output can't be read back from the hardware.
15  * - The hardware can only generate normal polarity output.
16  * - The period and duty cycle can't be changed together in one atomic action.
22 #include <linux/pwm.h>
27 	struct ntxec *ec;  member
44  * The time base used in the EC is 8MHz, or 125ns. Period and duty cycle are
66 	 * is longer than the new period, the EC may output 100% for a moment.  in ntxec_pwm_set_raw_period_and_duty_cycle()
79 	return regmap_multi_reg_write(priv->ec->regmap, regs, ARRAY_SIZE(regs));  in ntxec_pwm_set_raw_period_and_duty_cycle()
89 	if (state->polarity != PWM_POLARITY_NORMAL)  in ntxec_pwm_apply()
90 		return -EINVAL;  in ntxec_pwm_apply()
92 	period = min_t(u64, state->period, MAX_PERIOD_NS);  in ntxec_pwm_apply()
93 	duty   = min_t(u64, state->duty_cycle, period);  in ntxec_pwm_apply()
107 	if (state->enabled && duty != 0) {  in ntxec_pwm_apply()
112 		res = regmap_write(priv->ec->regmap, NTXEC_REG_ENABLE, ntxec_reg8(1));  in ntxec_pwm_apply()
116 		/* Disable the auto-off timer */  in ntxec_pwm_apply()
117 		res = regmap_write(priv->ec->regmap, NTXEC_REG_AUTO_OFF_HI, ntxec_reg8(0xff));  in ntxec_pwm_apply()
121 		return regmap_write(priv->ec->regmap, NTXEC_REG_AUTO_OFF_LO, ntxec_reg8(0xff));  in ntxec_pwm_apply()
123 		return regmap_write(priv->ec->regmap, NTXEC_REG_ENABLE, ntxec_reg8(0));  in ntxec_pwm_apply()
137 	struct ntxec *ec = dev_get_drvdata(pdev->dev.parent);  in ntxec_pwm_probe()  local
141 	device_set_of_node_from_dev(&pdev->dev, pdev->dev.parent);  in ntxec_pwm_probe()
143 	chip = devm_pwmchip_alloc(&pdev->dev, 1, sizeof(*priv));  in ntxec_pwm_probe()
148 	priv->ec = ec;  in ntxec_pwm_probe()
149 	chip->ops = &ntxec_pwm_ops;  in ntxec_pwm_probe()
151 	return devm_pwmchip_add(&pdev->dev, chip);  in ntxec_pwm_probe()
156 		.name = "ntxec-pwm",
163 MODULE_DESCRIPTION("PWM driver for Netronix EC");
165 MODULE_ALIAS("platform:ntxec-pwm");