1 files changed, 305 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-cros-ec.c b/drivers/pwm/pwm-cros-ec.c
new file mode 100644
index 000000000..d4f4a1336
--- /dev/null
+++ b/drivers/pwm/pwm-cros-ec.c
@@ -0,0 +1,305 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Expose a PWM controlled by the ChromeOS EC to the host processor.
+ *
+ * Copyright (C) 2016 Google, Inc.
+ */
+
+#include <linux/module.h>
+#include <linux/platform_data/cros_ec_commands.h>
+#include <linux/platform_data/cros_ec_proto.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/slab.h>
+
+/**
+ * struct cros_ec_pwm_device - Driver data for EC PWM
+ *
+ * @dev: Device node
+ * @ec: Pointer to EC device
+ * @chip: PWM controller chip
+ */
+struct cros_ec_pwm_device {
+	struct device *dev;
+	struct cros_ec_device *ec;
+	struct pwm_chip chip;
+};
+
+/**
+ * struct cros_ec_pwm - per-PWM driver data
+ * @duty_cycle: cached duty cycle
+ */
+struct cros_ec_pwm {
+	u16 duty_cycle;
+};
+
+static inline struct cros_ec_pwm_device *pwm_to_cros_ec_pwm(struct pwm_chip *c)
+{
+	return container_of(c, struct cros_ec_pwm_device, chip);
+}
+
+static int cros_ec_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct cros_ec_pwm *channel;
+
+	channel = kzalloc(sizeof(*channel), GFP_KERNEL);
+	if (!channel)
+		return -ENOMEM;
+
+	pwm_set_chip_data(pwm, channel);
+
+	return 0;
+}
+
+static void cros_ec_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct cros_ec_pwm *channel = pwm_get_chip_data(pwm);
+
+	kfree(channel);
+}
+
+static int cros_ec_pwm_set_duty(struct cros_ec_device *ec, u8 index, u16 duty)
+{
+	struct {
+		struct cros_ec_command msg;
+		struct ec_params_pwm_set_duty params;
+	} __packed buf;
+	struct ec_params_pwm_set_duty *params = &buf.params;
+	struct cros_ec_command *msg = &buf.msg;
+
+	memset(&buf, 0, sizeof(buf));
+
+	msg->version = 0;
+	msg->command = EC_CMD_PWM_SET_DUTY;
+	msg->insize = 0;
+	msg->outsize = sizeof(*params);
+
+	params->duty = duty;
+	params->pwm_type = EC_PWM_TYPE_GENERIC;
+	params->index = index;
+
+	return cros_ec_cmd_xfer_status(ec, msg);
+}
+
+static int cros_ec_pwm_get_duty(struct cros_ec_device *ec, u8 index)
+{
+	struct {
+		struct cros_ec_command msg;
+		union {
+			struct ec_params_pwm_get_duty params;
+			struct ec_response_pwm_get_duty resp;
+		};
+	} __packed buf;
+	struct ec_params_pwm_get_duty *params = &buf.params;
+	struct ec_response_pwm_get_duty *resp = &buf.resp;
+	struct cros_ec_command *msg = &buf.msg;
+	int ret;
+
+	memset(&buf, 0, sizeof(buf));
+
+	msg->version = 0;
+	msg->command = EC_CMD_PWM_GET_DUTY;
+	msg->insize = sizeof(*resp);
+	msg->outsize = sizeof(*params);
+
+	params->pwm_type = EC_PWM_TYPE_GENERIC;
+	params->index = index;
+
+	ret = cros_ec_cmd_xfer_status(ec, msg);
+	if (ret < 0)
+		return ret;
+
+	return resp->duty;
+}
+
+static int cros_ec_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+			     const struct pwm_state *state)
+{
+	struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip);
+	struct cros_ec_pwm *channel = pwm_get_chip_data(pwm);
+	u16 duty_cycle;
+	int ret;
+
+	/* The EC won't let us change the period */
+	if (state->period != EC_PWM_MAX_DUTY)
+		return -EINVAL;
+
+	/*
+	 * EC doesn't separate the concept of duty cycle and enabled, but
+	 * kernel does. Translate.
+	 */
+	duty_cycle = state->enabled ? state->duty_cycle : 0;
+
+	ret = cros_ec_pwm_set_duty(ec_pwm->ec, pwm->hwpwm, duty_cycle);
+	if (ret < 0)
+		return ret;
+
+	channel->duty_cycle = state->duty_cycle;
+
+	return 0;
+}
+
+static void cros_ec_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+				  struct pwm_state *state)
+{
+	struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip);
+	struct cros_ec_pwm *channel = pwm_get_chip_data(pwm);
+	int ret;
+
+	ret = cros_ec_pwm_get_duty(ec_pwm->ec, pwm->hwpwm);
+	if (ret < 0) {
+		dev_err(chip->dev, "error getting initial duty: %d\n", ret);
+		return;
+	}
+
+	state->enabled = (ret > 0);
+	state->period = EC_PWM_MAX_DUTY;
+	state->polarity = PWM_POLARITY_NORMAL;
+
+	/*
+	 * Note that "disabled" and "duty cycle == 0" are treated the same. If
+	 * the cached duty cycle is not zero, used the cached duty cycle. This
+	 * ensures that the configured duty cycle is kept across a disable and
+	 * enable operation and avoids potentially confusing consumers.
+	 *
+	 * For the case of the initial hardware readout, channel->duty_cycle
+	 * will be 0 and the actual duty cycle read from the EC is used.
+	 */
+	if (ret == 0 && channel->duty_cycle > 0)
+		state->duty_cycle = channel->duty_cycle;
+	else
+		state->duty_cycle = ret;
+}
+
+static struct pwm_device *
+cros_ec_pwm_xlate(struct pwm_chip *pc, const struct of_phandle_args *args)
+{
+	struct pwm_device *pwm;
+
+	if (args->args[0] >= pc->npwm)
+		return ERR_PTR(-EINVAL);
+
+	pwm = pwm_request_from_chip(pc, args->args[0], NULL);
+	if (IS_ERR(pwm))
+		return pwm;
+
+	/* The EC won't let us change the period */
+	pwm->args.period = EC_PWM_MAX_DUTY;
+
+	return pwm;
+}
+
+static const struct pwm_ops cros_ec_pwm_ops = {
+	.request = cros_ec_pwm_request,
+	.free = cros_ec_pwm_free,
+	.get_state	= cros_ec_pwm_get_state,
+	.apply		= cros_ec_pwm_apply,
+	.owner		= THIS_MODULE,
+};
+
+/*
+ * Determine the number of supported PWMs. The EC does not return the number
+ * of PWMs it supports directly, so we have to read the pwm duty cycle for
+ * subsequent channels until we get an error.
+ */
+static int cros_ec_num_pwms(struct cros_ec_device *ec)
+{
+	int i, ret;
+
+	/* The index field is only 8 bits */
+	for (i = 0; i <= U8_MAX; i++) {
+		ret = cros_ec_pwm_get_duty(ec, i);
+		/*
+		 * We look for SUCCESS, INVALID_COMMAND, or INVALID_PARAM
+		 * responses; everything else is treated as an error.
+		 * The EC error codes map to -EOPNOTSUPP and -EINVAL,
+		 * so check for those.
+		 */
+		switch (ret) {
+		case -EOPNOTSUPP:	/* invalid command */
+			return -ENODEV;
+		case -EINVAL:		/* invalid parameter */
+			return i;
+		default:
+			if (ret < 0)
+				return ret;
+			break;
+		}
+	}
+
+	return U8_MAX;
+}
+
+static int cros_ec_pwm_probe(struct platform_device *pdev)
+{
+	struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
+	struct device *dev = &pdev->dev;
+	struct cros_ec_pwm_device *ec_pwm;
+	struct pwm_chip *chip;
+	int ret;
+
+	if (!ec) {
+		dev_err(dev, "no parent EC device\n");
+		return -EINVAL;
+	}
+
+	ec_pwm = devm_kzalloc(dev, sizeof(*ec_pwm), GFP_KERNEL);
+	if (!ec_pwm)
+		return -ENOMEM;
+	chip = &ec_pwm->chip;
+	ec_pwm->ec = ec;
+
+	/* PWM chip */
+	chip->dev = dev;
+	chip->ops = &cros_ec_pwm_ops;
+	chip->of_xlate = cros_ec_pwm_xlate;
+	chip->of_pwm_n_cells = 1;
+	chip->base = -1;
+	ret = cros_ec_num_pwms(ec);
+	if (ret < 0) {
+		dev_err(dev, "Couldn't find PWMs: %d\n", ret);
+		return ret;
+	}
+	chip->npwm = ret;
+	dev_dbg(dev, "Probed %u PWMs\n", chip->npwm);
+
+	ret = pwmchip_add(chip);
+	if (ret < 0) {
+		dev_err(dev, "cannot register PWM: %d\n", ret);
+		return ret;
+	}
+
+	platform_set_drvdata(pdev, ec_pwm);
+
+	return ret;
+}
+
+static int cros_ec_pwm_remove(struct platform_device *dev)
+{
+	struct cros_ec_pwm_device *ec_pwm = platform_get_drvdata(dev);
+	struct pwm_chip *chip = &ec_pwm->chip;
+
+	return pwmchip_remove(chip);
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id cros_ec_pwm_of_match[] = {
+	{ .compatible = "google,cros-ec-pwm" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, cros_ec_pwm_of_match);
+#endif
+
+static struct platform_driver cros_ec_pwm_driver = {
+	.probe = cros_ec_pwm_probe,
+	.remove = cros_ec_pwm_remove,
+	.driver = {
+		.name = "cros-ec-pwm",
+		.of_match_table = of_match_ptr(cros_ec_pwm_of_match),
+	},
+};
+module_platform_driver(cros_ec_pwm_driver);
+
+MODULE_ALIAS("platform:cros-ec-pwm");
+MODULE_DESCRIPTION("ChromeOS EC PWM driver");
+MODULE_LICENSE("GPL v2");