1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Expose a PWM controlled by the ChromeOS EC to the host processor.
  4 *
  5 * Copyright (C) 2016 Google, Inc.
  6 */
  7
  8#include <linux/module.h>
  9#include <linux/platform_data/cros_ec_commands.h>
 10#include <linux/platform_data/cros_ec_proto.h>
 11#include <linux/platform_device.h>
 12#include <linux/pwm.h>
 13#include <linux/slab.h>
 14
 15/**
 16 * struct cros_ec_pwm_device - Driver data for EC PWM
 17 *
 18 * @dev: Device node
 19 * @ec: Pointer to EC device
 20 * @chip: PWM controller chip
 21 */
 22struct cros_ec_pwm_device {
 23	struct device *dev;
 24	struct cros_ec_device *ec;
 25	struct pwm_chip chip;
 26};
 27
 28static inline struct cros_ec_pwm_device *pwm_to_cros_ec_pwm(struct pwm_chip *c)
 29{
 30	return container_of(c, struct cros_ec_pwm_device, chip);
 31}
 32
 33static int cros_ec_pwm_set_duty(struct cros_ec_device *ec, u8 index, u16 duty)
 34{
 35	struct {
 36		struct cros_ec_command msg;
 37		struct ec_params_pwm_set_duty params;
 38	} __packed buf;
 39	struct ec_params_pwm_set_duty *params = &buf.params;
 40	struct cros_ec_command *msg = &buf.msg;
 41
 42	memset(&buf, 0, sizeof(buf));
 43
 44	msg->version = 0;
 45	msg->command = EC_CMD_PWM_SET_DUTY;
 46	msg->insize = 0;
 47	msg->outsize = sizeof(*params);
 48
 49	params->duty = duty;
 50	params->pwm_type = EC_PWM_TYPE_GENERIC;
 51	params->index = index;
 52
 53	return cros_ec_cmd_xfer_status(ec, msg);
 54}
 55
 56static int __cros_ec_pwm_get_duty(struct cros_ec_device *ec, u8 index,
 57				  u32 *result)
 58{
 59	struct {
 60		struct cros_ec_command msg;
 61		union {
 62			struct ec_params_pwm_get_duty params;
 63			struct ec_response_pwm_get_duty resp;
 64		};
 65	} __packed buf;
 66	struct ec_params_pwm_get_duty *params = &buf.params;
 67	struct ec_response_pwm_get_duty *resp = &buf.resp;
 68	struct cros_ec_command *msg = &buf.msg;
 69	int ret;
 70
 71	memset(&buf, 0, sizeof(buf));
 72
 73	msg->version = 0;
 74	msg->command = EC_CMD_PWM_GET_DUTY;
 75	msg->insize = sizeof(*resp);
 76	msg->outsize = sizeof(*params);
 77
 78	params->pwm_type = EC_PWM_TYPE_GENERIC;
 79	params->index = index;
 80
 81	ret = cros_ec_cmd_xfer_status(ec, msg);
 82	if (result)
 83		*result = msg->result;
 84	if (ret < 0)
 85		return ret;
 86
 87	return resp->duty;
 88}
 89
 90static int cros_ec_pwm_get_duty(struct cros_ec_device *ec, u8 index)
 91{
 92	return __cros_ec_pwm_get_duty(ec, index, NULL);
 93}
 94
 95static int cros_ec_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 96			     const struct pwm_state *state)
 97{
 98	struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip);
 99	int duty_cycle;
100
101	/* The EC won't let us change the period */
102	if (state->period != EC_PWM_MAX_DUTY)
103		return -EINVAL;
104
105	/*
106	 * EC doesn't separate the concept of duty cycle and enabled, but
107	 * kernel does. Translate.
108	 */
109	duty_cycle = state->enabled ? state->duty_cycle : 0;
110
111	return cros_ec_pwm_set_duty(ec_pwm->ec, pwm->hwpwm, duty_cycle);
112}
113
114static void cros_ec_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
115				  struct pwm_state *state)
116{
117	struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip);
118	int ret;
119
120	ret = cros_ec_pwm_get_duty(ec_pwm->ec, pwm->hwpwm);
121	if (ret < 0) {
122		dev_err(chip->dev, "error getting initial duty: %d\n", ret);
123		return;
124	}
125
126	state->enabled = (ret > 0);
127	state->period = EC_PWM_MAX_DUTY;
128
129	/* Note that "disabled" and "duty cycle == 0" are treated the same */
130	state->duty_cycle = ret;
131}
132
133static struct pwm_device *
134cros_ec_pwm_xlate(struct pwm_chip *pc, const struct of_phandle_args *args)
135{
136	struct pwm_device *pwm;
137
138	if (args->args[0] >= pc->npwm)
139		return ERR_PTR(-EINVAL);
140
141	pwm = pwm_request_from_chip(pc, args->args[0], NULL);
142	if (IS_ERR(pwm))
143		return pwm;
144
145	/* The EC won't let us change the period */
146	pwm->args.period = EC_PWM_MAX_DUTY;
147
148	return pwm;
149}
150
151static const struct pwm_ops cros_ec_pwm_ops = {
152	.get_state	= cros_ec_pwm_get_state,
153	.apply		= cros_ec_pwm_apply,
154	.owner		= THIS_MODULE,
155};
156
157static int cros_ec_num_pwms(struct cros_ec_device *ec)
158{
159	int i, ret;
160
161	/* The index field is only 8 bits */
162	for (i = 0; i <= U8_MAX; i++) {
163		u32 result = 0;
164
165		ret = __cros_ec_pwm_get_duty(ec, i, &result);
166		/* We want to parse EC protocol errors */
167		if (ret < 0 && !(ret == -EPROTO && result))
168			return ret;
169
170		/*
171		 * We look for SUCCESS, INVALID_COMMAND, or INVALID_PARAM
172		 * responses; everything else is treated as an error.
173		 */
174		if (result == EC_RES_INVALID_COMMAND)
175			return -ENODEV;
176		else if (result == EC_RES_INVALID_PARAM)
177			return i;
178		else if (result)
179			return -EPROTO;
180	}
181
182	return U8_MAX;
183}
184
185static int cros_ec_pwm_probe(struct platform_device *pdev)
186{
187	struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
188	struct device *dev = &pdev->dev;
189	struct cros_ec_pwm_device *ec_pwm;
190	struct pwm_chip *chip;
191	int ret;
192
193	if (!ec) {
194		dev_err(dev, "no parent EC device\n");
195		return -EINVAL;
196	}
197
198	ec_pwm = devm_kzalloc(dev, sizeof(*ec_pwm), GFP_KERNEL);
199	if (!ec_pwm)
200		return -ENOMEM;
201	chip = &ec_pwm->chip;
202	ec_pwm->ec = ec;
203
204	/* PWM chip */
205	chip->dev = dev;
206	chip->ops = &cros_ec_pwm_ops;
207	chip->of_xlate = cros_ec_pwm_xlate;
208	chip->of_pwm_n_cells = 1;
209	chip->base = -1;
210	ret = cros_ec_num_pwms(ec);
211	if (ret < 0) {
212		dev_err(dev, "Couldn't find PWMs: %d\n", ret);
213		return ret;
214	}
215	chip->npwm = ret;
216	dev_dbg(dev, "Probed %u PWMs\n", chip->npwm);
217
218	ret = pwmchip_add(chip);
219	if (ret < 0) {
220		dev_err(dev, "cannot register PWM: %d\n", ret);
221		return ret;
222	}
223
224	platform_set_drvdata(pdev, ec_pwm);
225
226	return ret;
227}
228
229static int cros_ec_pwm_remove(struct platform_device *dev)
230{
231	struct cros_ec_pwm_device *ec_pwm = platform_get_drvdata(dev);
232	struct pwm_chip *chip = &ec_pwm->chip;
233
234	return pwmchip_remove(chip);
235}
236
237#ifdef CONFIG_OF
238static const struct of_device_id cros_ec_pwm_of_match[] = {
239	{ .compatible = "google,cros-ec-pwm" },
240	{},
241};
242MODULE_DEVICE_TABLE(of, cros_ec_pwm_of_match);
243#endif
244
245static struct platform_driver cros_ec_pwm_driver = {
246	.probe = cros_ec_pwm_probe,
247	.remove = cros_ec_pwm_remove,
248	.driver = {
249		.name = "cros-ec-pwm",
250		.of_match_table = of_match_ptr(cros_ec_pwm_of_match),
251	},
252};
253module_platform_driver(cros_ec_pwm_driver);
254
255MODULE_ALIAS("platform:cros-ec-pwm");
256MODULE_DESCRIPTION("ChromeOS EC PWM driver");
257MODULE_LICENSE("GPL v2");