greybus: add pwm protocol driver

Add a PWM driver that implements the Greybus PWM protocol.
Signed-off-by: Matt Porter <mporter@linaro.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

drivers/staging/greybus/Makefile

@@ -11,6 +11,7 @@ greybus-y :=	core.o		\
 		operation.o	\
 		i2c-gb.o	\
 		gpio-gb.o	\
+		pwm-gb.o	\
 		sdio-gb.o	\
 		uart-gb.o	\
 		battery-gb.o

drivers/staging/greybus/greybus_manifest.h

@@ -32,6 +32,7 @@ enum greybus_protocol {
 	GREYBUS_PROTOCOL_HID		= 0x05,
 	GREYBUS_PROTOCOL_SDIO		= 0x06,
 	GREYBUS_PROTOCOL_BATTERY	= 0x08,
+	GREYBUS_PROTOCOL_PWM		= 0x09,
 	GREYBUS_PROTOCOL_LED		= 0x0e,
 		/* ... */
 	GREYBUS_PROTOCOL_VENDOR		= 0xff,

drivers/staging/greybus/protocol.c

@@ -177,6 +177,10 @@ bool gb_protocol_init(void)
 		pr_err("error initializing i2c protocol\n");
 		ret = false;
 	}
+	if (!gb_pwm_protocol_init()) {
+		pr_err("error initializing pwm protocol\n");
+		ret = false;
+	}
 	if (!gb_uart_protocol_init()) {
 		pr_err("error initializing uart protocol\n");
 		ret = false;

drivers/staging/greybus/protocol.h

@@ -55,6 +55,9 @@ extern void gb_gpio_protocol_exit(void);
 extern bool gb_i2c_protocol_init(void);
 extern void gb_i2c_protocol_exit(void);
 
+extern bool gb_pwm_protocol_init(void);
+extern void gb_pwm_protocol_exit(void);
+
 extern bool gb_uart_protocol_init(void);
 extern void gb_uart_protocol_exit(void);
 

drivers/staging/greybus/pwm-gb.c

+/*
+ * PWM Greybus driver.
+ *
+ * Copyright 2014 Google Inc.
+ * Copyright 2014 Linaro Ltd.
+ *
+ * Released under the GPLv2 only.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/pwm.h>
+#include "greybus.h"
+
+struct gb_pwm_chip {
+	struct gb_connection	*connection;
+	u8			version_major;
+	u8			version_minor;
+	u8			pwm_max;	/* max pwm number */
+
+	struct pwm_chip		chip;
+	struct pwm_chip		*pwm;
+};
+#define pwm_chip_to_gb_pwm_chip(chip) \
+	container_of(chip, struct gb_pwm_chip, chip)
+
+/* Version of the Greybus PWM protocol we support */
+#define	GB_PWM_VERSION_MAJOR		0x00
+#define	GB_PWM_VERSION_MINOR		0x01
+
+/* Greybus PWM request types */
+#define	GB_PWM_TYPE_INVALID		0x00
+#define	GB_PWM_TYPE_PROTOCOL_VERSION	0x01
+#define	GB_PWM_TYPE_PWM_COUNT		0x02
+#define	GB_PWM_TYPE_ACTIVATE		0x03
+#define	GB_PWM_TYPE_DEACTIVATE		0x04
+#define	GB_PWM_TYPE_CONFIG		0x05
+#define	GB_PWM_TYPE_POLARITY		0x06
+#define	GB_PWM_TYPE_ENABLE		0x07
+#define	GB_PWM_TYPE_DISABLE		0x08
+#define	GB_PWM_TYPE_RESPONSE		0x80	/* OR'd with rest */
+
+struct gb_pwm_simple_response {
+	__u8	status;
+};
+
+/* version request has no payload */
+struct gb_pwm_proto_version_response {
+	__u8	status;
+	__u8	major;
+	__u8	minor;
+};
+
+/* pwm count request has no payload */
+struct gb_pwm_count_response {
+	__u8	status;
+	__u8	count;
+};
+
+struct gb_pwm_activate_request {
+	__u8	which;
+};
+
+struct gb_pwm_deactivate_request {
+	__u8	which;
+};
+
+struct gb_pwm_config_request {
+	__u8	which;
+	__u32	duty;
+	__u32	period;
+};
+
+struct gb_pwm_polarity_request {
+	__u8	which;
+	__u8	polarity;
+};
+
+struct gb_pwm_enable_request {
+	__u8	which;
+};
+
+struct gb_pwm_disable_request {
+	__u8	which;
+};
+
+/*
+ * This request only uses the connection field, and if successful,
+ * fills in the major and minor protocol version of the target.
+ */
+static int gb_pwm_proto_version_operation(struct gb_pwm_chip *pwmc)
+{
+	struct gb_connection *connection = pwmc->connection;
+	struct gb_operation *operation;
+	struct gb_pwm_proto_version_response *response;
+	int ret;
+
+	/* protocol version request has no payload */
+	operation = gb_operation_create(connection,
+					GB_PWM_TYPE_PROTOCOL_VERSION,
+					0, sizeof(*response));
+	if (!operation)
+		return -ENOMEM;
+
+	/* Synchronous operation--no callback */
+	ret = gb_operation_request_send(operation, NULL);
+	if (ret) {
+		pr_err("version operation failed (%d)\n", ret);
+		goto out;
+	}
+
+	response = operation->response_payload;
+	if (response->status) {
+		gb_connection_err(connection, "version response %hhu",
+				  response->status);
+		ret = -EIO;
+	} else {
+		if (response->major > GB_PWM_VERSION_MAJOR) {
+			pr_err("unsupported major version (%hhu > %hhu)\n",
+				response->major, GB_PWM_VERSION_MAJOR);
+			ret = -ENOTSUPP;
+			goto out;
+		}
+		pwmc->version_major = response->major;
+		pwmc->version_minor = response->minor;
+	}
+out:
+	gb_operation_destroy(operation);
+
+	return ret;
+}
+
+static int gb_pwm_count_operation(struct gb_pwm_chip *pwmc)
+{
+	struct gb_connection *connection = pwmc->connection;
+	struct gb_operation *operation;
+	struct gb_pwm_count_response *response;
+	int ret;
+
+	/* pwm count request has no payload */
+	operation = gb_operation_create(connection, GB_PWM_TYPE_PWM_COUNT,
+					0, sizeof(*response));
+	if (!operation)
+		return -ENOMEM;
+
+	/* Synchronous operation--no callback */
+	ret = gb_operation_request_send(operation, NULL);
+	if (ret) {
+		pr_err("line count operation failed (%d)\n", ret);
+		goto out;
+	}
+
+	response = operation->response_payload;
+	if (response->status) {
+		gb_connection_err(connection, "pwm count response %hhu",
+				  response->status);
+		ret = -EIO;
+	} else
+		pwmc->pwm_max = response->count;
+out:
+	gb_operation_destroy(operation);
+
+	return ret;
+}
+
+static int gb_pwm_activate_operation(struct gb_pwm_chip *pwmc,
+				     u8 which)
+{
+	struct gb_connection *connection = pwmc->connection;
+	struct gb_operation *operation;
+	struct gb_pwm_activate_request *request;
+	struct gb_pwm_simple_response *response;
+	int ret;
+
+	if (which > pwmc->pwm_max)
+		return -EINVAL;
+
+	/* activate response has no payload */
+	operation = gb_operation_create(connection, GB_PWM_TYPE_ACTIVATE,
+					sizeof(*request), sizeof(*response));
+	if (!operation)
+		return -ENOMEM;
+	request = operation->request_payload;
+	request->which = which;
+
+	/* Synchronous operation--no callback */
+	ret = gb_operation_request_send(operation, NULL);
+	if (ret) {
+		pr_err("activate operation failed (%d)\n", ret);
+		goto out;
+	}
+
+	response = operation->response_payload;
+	if (response->status) {
+		gb_connection_err(connection, "activate response %hhu",
+				  response->status);
+		ret = -EIO;
+	}
+out:
+	gb_operation_destroy(operation);
+
+	return ret;
+}
+
+static int gb_pwm_deactivate_operation(struct gb_pwm_chip *pwmc,
+				       u8 which)
+{
+	struct gb_connection *connection = pwmc->connection;
+	struct gb_operation *operation;
+	struct gb_pwm_deactivate_request *request;
+	struct gb_pwm_simple_response *response;
+	int ret;
+
+	if (which > pwmc->pwm_max)
+		return -EINVAL;
+
+	/* deactivate response has no payload */
+	operation = gb_operation_create(connection, GB_PWM_TYPE_DEACTIVATE,
+					sizeof(*request), sizeof(*response));
+	if (!operation)
+		return -ENOMEM;
+	request = operation->request_payload;
+	request->which = which;
+
+	/* Synchronous operation--no callback */
+	ret = gb_operation_request_send(operation, NULL);
+	if (ret) {
+		pr_err("deactivate operation failed (%d)\n", ret);
+		goto out;
+	}
+
+	response = operation->response_payload;
+	if (response->status) {
+		gb_connection_err(connection, "deactivate response %hhu",
+				  response->status);
+		ret = -EIO;
+	}
+out:
+	gb_operation_destroy(operation);
+
+	return ret;
+}
+
+static int gb_pwm_config_operation(struct gb_pwm_chip *pwmc,
+				   u8 which, u32 duty, u32 period)
+{
+	struct gb_connection *connection = pwmc->connection;
+	struct gb_operation *operation;
+	struct gb_pwm_config_request *request;
+	struct gb_pwm_simple_response *response;
+	int ret;
+
+	if (which > pwmc->pwm_max)
+		return -EINVAL;
+
+	operation = gb_operation_create(connection, GB_PWM_TYPE_CONFIG,
+					sizeof(*request), sizeof(*response));
+	if (!operation)
+		return -ENOMEM;
+	request = operation->request_payload;
+	request->which = which;
+	request->duty = duty;
+	request->period = period;
+
+	/* Synchronous operation--no callback */
+	ret = gb_operation_request_send(operation, NULL);
+	if (ret) {
+		pr_err("config operation failed (%d)\n", ret);
+		goto out;
+	}
+
+	response = operation->response_payload;
+	if (response->status) {
+		gb_connection_err(connection, "config response %hhu",
+				  response->status);
+		ret = -EIO;
+	}
+out:
+	gb_operation_destroy(operation);
+
+	return ret;
+}
+
+
+static int gb_pwm_set_polarity_operation(struct gb_pwm_chip *pwmc,
+					 u8 which, u8 polarity)
+{
+	struct gb_connection *connection = pwmc->connection;
+	struct gb_operation *operation;
+	struct gb_pwm_polarity_request *request;
+	struct gb_pwm_simple_response *response;
+	int ret;
+
+	if (which > pwmc->pwm_max)
+		return -EINVAL;
+
+	operation = gb_operation_create(connection, GB_PWM_TYPE_POLARITY,
+					sizeof(*request), sizeof(*response));
+	if (!operation)
+		return -ENOMEM;
+	request = operation->request_payload;
+	request->which = which;
+	request->polarity = polarity;
+
+	/* Synchronous operation--no callback */
+	ret = gb_operation_request_send(operation, NULL);
+	if (ret) {
+		pr_err("set polarity operation failed (%d)\n", ret);
+		goto out;
+	}
+
+	response = operation->response_payload;
+	if (response->status) {
+		gb_connection_err(connection, "set polarity response %hhu",
+				  response->status);
+		ret = -EIO;
+	}
+out:
+	gb_operation_destroy(operation);
+
+	return ret;
+}
+
+static int gb_pwm_enable_operation(struct gb_pwm_chip *pwmc,
+				   u8 which)
+{
+	struct gb_connection *connection = pwmc->connection;
+	struct gb_operation *operation;
+	struct gb_pwm_enable_request *request;
+	struct gb_pwm_simple_response *response;
+	int ret;
+
+	if (which > pwmc->pwm_max)
+		return -EINVAL;
+
+	/* enable response has no payload */
+	operation = gb_operation_create(connection, GB_PWM_TYPE_ENABLE,
+					sizeof(*request), sizeof(*response));
+	if (!operation)
+		return -ENOMEM;
+	request = operation->request_payload;
+	request->which = which;
+
+	/* Synchronous operation--no callback */
+	ret = gb_operation_request_send(operation, NULL);
+	if (ret) {
+		pr_err("enable operation failed (%d)\n", ret);
+		goto out;
+	}
+
+	response = operation->response_payload;
+	if (response->status) {
+		gb_connection_err(connection, "enable response %hhu",
+				  response->status);
+		ret = -EIO;
+	}
+out:
+	gb_operation_destroy(operation);
+
+	return ret;
+}
+
+static int gb_pwm_disable_operation(struct gb_pwm_chip *pwmc,
+				    u8 which)
+{
+	struct gb_connection *connection = pwmc->connection;
+	struct gb_operation *operation;
+	struct gb_pwm_disable_request *request;
+	struct gb_pwm_simple_response *response;
+	int ret;
+
+	if (which > pwmc->pwm_max)
+		return -EINVAL;
+
+	/* disable response has no payload */
+	operation = gb_operation_create(connection, GB_PWM_TYPE_DISABLE,
+					sizeof(*request), sizeof(*response));
+	if (!operation)
+		return -ENOMEM;
+	request = operation->request_payload;
+	request->which = which;
+
+	/* Synchronous operation--no callback */
+	ret = gb_operation_request_send(operation, NULL);
+	if (ret) {
+		pr_err("disable operation failed (%d)\n", ret);
+		goto out;
+	}
+
+	response = operation->response_payload;
+	if (response->status) {
+		gb_connection_err(connection, "disable response %hhu",
+				  response->status);
+		ret = -EIO;
+	}
+out:
+	gb_operation_destroy(operation);
+
+	return ret;
+}
+
+static int gb_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct gb_pwm_chip *pwmc = pwm_chip_to_gb_pwm_chip(chip);
+
+	return gb_pwm_activate_operation(pwmc, pwm->hwpwm);
+};
+
+static void gb_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct gb_pwm_chip *pwmc = pwm_chip_to_gb_pwm_chip(chip);
+
+	if (test_bit(PWMF_ENABLED, &pwm->flags))
+		dev_warn(chip->dev, "freeing PWM device without disabling\n");
+
+	gb_pwm_deactivate_operation(pwmc, pwm->hwpwm);
+}
+
+static int gb_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
+			 int duty_ns, int period_ns)
+{
+	struct gb_pwm_chip *pwmc = pwm_chip_to_gb_pwm_chip(chip);
+
+	return gb_pwm_config_operation(pwmc, pwm->hwpwm, duty_ns, period_ns);
+};
+
+static int gb_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
+			       enum pwm_polarity polarity)
+{
+	struct gb_pwm_chip *pwmc = pwm_chip_to_gb_pwm_chip(chip);
+
+	return gb_pwm_set_polarity_operation(pwmc, pwm->hwpwm, polarity);
+};
+
+static int gb_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct gb_pwm_chip *pwmc = pwm_chip_to_gb_pwm_chip(chip);
+
+	return gb_pwm_enable_operation(pwmc, pwm->hwpwm);
+};
+
+static void gb_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct gb_pwm_chip *pwmc = pwm_chip_to_gb_pwm_chip(chip);
+
+	gb_pwm_disable_operation(pwmc, pwm->hwpwm);
+};
+
+static const struct pwm_ops gb_pwm_ops = {
+	.request = gb_pwm_request,
+	.free = gb_pwm_free,
+	.config = gb_pwm_config,
+	.set_polarity = gb_pwm_set_polarity,
+	.enable = gb_pwm_enable,
+	.disable = gb_pwm_disable,
+	.owner = THIS_MODULE,
+};
+
+static int gb_pwm_connection_init(struct gb_connection *connection)
+{
+	struct gb_pwm_chip *pwmc;
+	struct pwm_chip *pwm;
+	int ret;
+
+	pwmc = kzalloc(sizeof(*pwmc), GFP_KERNEL);
+	if (!pwmc)
+		return -ENOMEM;
+	pwmc->connection = connection;
+
+	/* Check for compatible protocol version */
+	ret = gb_pwm_proto_version_operation(pwmc);
+	if (ret)
+		goto out_err;
+
+	/* Query number of pwms present */
+	ret = gb_pwm_count_operation(pwmc);
+	if (ret)
+		goto out_err;
+
+	pwm = &pwmc->chip;
+
+	pwm->dev = &connection->dev;
+	pwm->ops = &gb_pwm_ops;
+	pwm->base = -1;			/* Allocate base dynamically */
+	pwm->npwm = pwmc->pwm_max + 1;
+	pwm->can_sleep = true;		/* FIXME */
+
+	ret = pwmchip_add(pwm);
+	if (ret) {
+		pr_err("Failed to register PWM\n");
+		return ret;
+	}
+	connection->private = pwmc;
+
+	return 0;
+out_err:
+	kfree(pwmc);
+	return ret;
+}
+
+static void gb_pwm_connection_exit(struct gb_connection *connection)
+{
+	struct gb_pwm_chip *pwmc = connection->private;
+
+	if (!pwmc)
+		return;
+
+	pwmchip_remove(&pwmc->chip);
+	/* kref_put(pwmc->connection) */
+	kfree(pwmc);
+}
+
+static struct gb_protocol pwm_protocol = {
+	.id			= GREYBUS_PROTOCOL_PWM,
+	.major			= 0,
+	.minor			= 1,
+	.connection_init	= gb_pwm_connection_init,
+	.connection_exit	= gb_pwm_connection_exit,
+	.request_recv		= NULL, /* no incoming requests */
+};
+
+bool gb_pwm_protocol_init(void)
+{
+	return gb_protocol_register(&pwm_protocol);
+}
+
+void gb_pwm_protocol_exit(void)
+{
+	gb_protocol_deregister(&pwm_protocol);
+}