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From:   Stephen Boyd <swboyd@chromium.org>
To:     Benson Leung <bleung@chromium.org>,
        Enric Balletbo i Serra <enric.balletbo@collabora.com>
Cc:     linux-kernel@vger.kernel.org,
        Gwendal Grignou <gwendal@chromium.org>,
        Guenter Roeck <groeck@chromium.org>,
        Lee Jones <lee.jones@linaro.org>
Subject: [PATCH] platform/chrome: Don't populate lightbar device if it isn't there
Date:   Wed,  9 Sep 2020 13:26:09 -0700
Message-Id: <20200909202609.1630698-1-swboyd@chromium.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

The cros ec lightbar driver has a check in probe to fail early if the ec
device isn't the cros_ec one or if it can't read the lightbar version
from the EC. Let's move this check to the place where the lightbar
device is registered. This way we don't expose devices that aren't
actually there on devices that don't have a lightbar.

This should improve memory and possibly performance too because struct
devices don't exactly have a small memory footprint and they contribute
to suspend/resume regardless of driver attachment.

Cc: Gwendal Grignou <gwendal@chromium.org>
Cc: Guenter Roeck <groeck@chromium.org>
Cc: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
---
 drivers/mfd/cros_ec_dev.c                   |  16 +++-
 drivers/platform/chrome/cros_ec_lightbar.c  | 100 ++------------------
 drivers/platform/chrome/cros_ec_proto.c     |  82 ++++++++++++++++
 include/linux/platform_data/cros_ec_proto.h |   4 +
 4 files changed, 109 insertions(+), 93 deletions(-)

diff --git a/drivers/mfd/cros_ec_dev.c b/drivers/mfd/cros_ec_dev.c
index d07b43d7c761..9e98b2ec5d92 100644
--- a/drivers/mfd/cros_ec_dev.c
+++ b/drivers/mfd/cros_ec_dev.c
@@ -74,6 +74,10 @@ static const struct mfd_cell cros_ec_cec_cells[] = {
 	{ .name = "cros-ec-cec", },
 };
 
+static const struct mfd_cell cros_ec_lightbar_cells[] = {
+	{ .name = "cros-ec-lightbar", },
+};
+
 static const struct mfd_cell cros_ec_rtc_cells[] = {
 	{ .name = "cros-ec-rtc", },
 };
@@ -112,7 +116,6 @@ static const struct cros_feature_to_cells cros_subdevices[] = {
 static const struct mfd_cell cros_ec_platform_cells[] = {
 	{ .name = "cros-ec-chardev", },
 	{ .name = "cros-ec-debugfs", },
-	{ .name = "cros-ec-lightbar", },
 	{ .name = "cros-ec-sysfs", },
 };
 
@@ -206,6 +209,17 @@ static int ec_device_probe(struct platform_device *pdev)
 		}
 	}
 
+	if (!strcmp(ec_platform->ec_name, CROS_EC_DEV_NAME) &&
+	    !cros_ec_get_lightbar_version(ec, NULL, NULL)) {
+		retval = mfd_add_hotplug_devices(ec->dev,
+				cros_ec_lightbar_cells,
+				ARRAY_SIZE(cros_ec_lightbar_cells));
+		if (retval)
+			dev_err(ec->dev,
+				"failed to add lightbar	device: %d\n",
+				retval);
+	}
+
 	/*
 	 * The PD notifier driver cell is separate since it only needs to be
 	 * explicitly added on platforms that don't have the PD notifier ACPI
diff --git a/drivers/platform/chrome/cros_ec_lightbar.c b/drivers/platform/chrome/cros_ec_lightbar.c
index b59180bff5a3..95e2e62bea9b 100644
--- a/drivers/platform/chrome/cros_ec_lightbar.c
+++ b/drivers/platform/chrome/cros_ec_lightbar.c
@@ -82,75 +82,6 @@ static int lb_throttle(void)
 	return ret;
 }
 
-static struct cros_ec_command *alloc_lightbar_cmd_msg(struct cros_ec_dev *ec)
-{
-	struct cros_ec_command *msg;
-	int len;
-
-	len = max(sizeof(struct ec_params_lightbar),
-		  sizeof(struct ec_response_lightbar));
-
-	msg = kmalloc(sizeof(*msg) + len, GFP_KERNEL);
-	if (!msg)
-		return NULL;
-
-	msg->version = 0;
-	msg->command = EC_CMD_LIGHTBAR_CMD + ec->cmd_offset;
-	msg->outsize = sizeof(struct ec_params_lightbar);
-	msg->insize = sizeof(struct ec_response_lightbar);
-
-	return msg;
-}
-
-static int get_lightbar_version(struct cros_ec_dev *ec,
-				uint32_t *ver_ptr, uint32_t *flg_ptr)
-{
-	struct ec_params_lightbar *param;
-	struct ec_response_lightbar *resp;
-	struct cros_ec_command *msg;
-	int ret;
-
-	msg = alloc_lightbar_cmd_msg(ec);
-	if (!msg)
-		return 0;
-
-	param = (struct ec_params_lightbar *)msg->data;
-	param->cmd = LIGHTBAR_CMD_VERSION;
-	ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
-	if (ret < 0) {
-		ret = 0;
-		goto exit;
-	}
-
-	switch (msg->result) {
-	case EC_RES_INVALID_PARAM:
-		/* Pixel had no version command. */
-		if (ver_ptr)
-			*ver_ptr = 0;
-		if (flg_ptr)
-			*flg_ptr = 0;
-		ret = 1;
-		goto exit;
-
-	case EC_RES_SUCCESS:
-		resp = (struct ec_response_lightbar *)msg->data;
-
-		/* Future devices w/lightbars should implement this command */
-		if (ver_ptr)
-			*ver_ptr = resp->version.num;
-		if (flg_ptr)
-			*flg_ptr = resp->version.flags;
-		ret = 1;
-		goto exit;
-	}
-
-	/* Anything else (ie, EC_RES_INVALID_COMMAND) - no lightbar */
-	ret = 0;
-exit:
-	kfree(msg);
-	return ret;
-}
-
 static ssize_t version_show(struct device *dev,
 			    struct device_attribute *attr, char *buf)
 {
@@ -163,7 +94,7 @@ static ssize_t version_show(struct device *dev,
 		return ret;
 
 	/* This should always succeed, because we check during init. */
-	if (!get_lightbar_version(ec, &version, &flags))
+	if (cros_ec_get_lightbar_version(ec, &version, &flags))
 		return -EIO;
 
 	return scnprintf(buf, PAGE_SIZE, "%d %d\n", version, flags);
@@ -182,7 +113,7 @@ static ssize_t brightness_store(struct device *dev,
 	if (kstrtouint(buf, 0, &val))
 		return -EINVAL;
 
-	msg = alloc_lightbar_cmd_msg(ec);
+	msg = cros_ec_alloc_lightbar_cmd_msg(ec);
 	if (!msg)
 		return -ENOMEM;
 
@@ -220,7 +151,7 @@ static ssize_t led_rgb_store(struct device *dev, struct device_attribute *attr,
 	unsigned int val[4];
 	int ret, i = 0, j = 0, ok = 0;
 
-	msg = alloc_lightbar_cmd_msg(ec);
+	msg = cros_ec_alloc_lightbar_cmd_msg(ec);
 	if (!msg)
 		return -ENOMEM;
 
@@ -287,7 +218,7 @@ static ssize_t sequence_show(struct device *dev,
 	int ret;
 	struct cros_ec_dev *ec = to_cros_ec_dev(dev);
 
-	msg = alloc_lightbar_cmd_msg(ec);
+	msg = cros_ec_alloc_lightbar_cmd_msg(ec);
 	if (!msg)
 		return -ENOMEM;
 
@@ -324,7 +255,7 @@ static int lb_send_empty_cmd(struct cros_ec_dev *ec, uint8_t cmd)
 	struct cros_ec_command *msg;
 	int ret;
 
-	msg = alloc_lightbar_cmd_msg(ec);
+	msg = cros_ec_alloc_lightbar_cmd_msg(ec);
 	if (!msg)
 		return -ENOMEM;
 
@@ -352,7 +283,7 @@ static int lb_manual_suspend_ctrl(struct cros_ec_dev *ec, uint8_t enable)
 	struct cros_ec_command *msg;
 	int ret;
 
-	msg = alloc_lightbar_cmd_msg(ec);
+	msg = cros_ec_alloc_lightbar_cmd_msg(ec);
 	if (!msg)
 		return -ENOMEM;
 
@@ -399,7 +330,7 @@ static ssize_t sequence_store(struct device *dev, struct device_attribute *attr,
 			return ret;
 	}
 
-	msg = alloc_lightbar_cmd_msg(ec);
+	msg = cros_ec_alloc_lightbar_cmd_msg(ec);
 	if (!msg)
 		return -ENOMEM;
 
@@ -444,7 +375,7 @@ static ssize_t program_store(struct device *dev, struct device_attribute *attr,
 		return -EINVAL;
 	}
 
-	msg = alloc_lightbar_cmd_msg(ec);
+	msg = cros_ec_alloc_lightbar_cmd_msg(ec);
 	if (!msg)
 		return -ENOMEM;
 
@@ -531,24 +462,9 @@ static struct attribute_group cros_ec_lightbar_attr_group = {
 static int cros_ec_lightbar_probe(struct platform_device *pd)
 {
 	struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent);
-	struct cros_ec_platform *pdata = dev_get_platdata(ec_dev->dev);
 	struct device *dev = &pd->dev;
 	int ret;
 
-	/*
-	 * Only instantiate the lightbar if the EC name is 'cros_ec'. Other EC
-	 * devices like 'cros_pd' doesn't have a lightbar.
-	 */
-	if (strcmp(pdata->ec_name, CROS_EC_DEV_NAME) != 0)
-		return -ENODEV;
-
-	/*
-	 * Ask then for the lightbar version, if it's 0 then the 'cros_ec'
-	 * doesn't have a lightbar.
-	 */
-	if (!get_lightbar_version(ec_dev, NULL, NULL))
-		return -ENODEV;
-
 	/* Take control of the lightbar from the EC. */
 	lb_manual_suspend_ctrl(ec_dev, 1);
 
diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c
index 8d52b3b4bd4e..7a297a527f8d 100644
--- a/drivers/platform/chrome/cros_ec_proto.c
+++ b/drivers/platform/chrome/cros_ec_proto.c
@@ -887,3 +887,85 @@ int cros_ec_get_sensor_count(struct cros_ec_dev *ec)
 	return sensor_count;
 }
 EXPORT_SYMBOL_GPL(cros_ec_get_sensor_count);
+
+struct cros_ec_command *cros_ec_alloc_lightbar_cmd_msg(struct cros_ec_dev *ec)
+{
+	struct cros_ec_command *msg;
+	int len;
+
+	len = max(sizeof(struct ec_params_lightbar),
+		  sizeof(struct ec_response_lightbar));
+
+	msg = kmalloc(sizeof(*msg) + len, GFP_KERNEL);
+	if (!msg)
+		return NULL;
+
+	msg->version = 0;
+	msg->command = EC_CMD_LIGHTBAR_CMD + ec->cmd_offset;
+	msg->outsize = sizeof(struct ec_params_lightbar);
+	msg->insize = sizeof(struct ec_response_lightbar);
+
+	return msg;
+}
+EXPORT_SYMBOL_GPL(cros_ec_alloc_lightbar_cmd_msg);
+
+/**
+ * cros_ec_get_lightbar_version() - Get the EC lightbar version
+ *
+ * @ec: EC device, does not have to be connected directly to the AP,
+ *      can be daisy chained through another device.
+ * @ver_ptr: Detected lightbar version number
+ * @flag_ptr: Detected lightbar flags
+ *
+ * Call this function to determine the EC's lightbar version and flags
+ * information. If it doesn't exist then this function returns a negative
+ * error value.
+ *
+ * Return: 0 on success, negative errno on failure to detect a lightbar.
+ */
+int cros_ec_get_lightbar_version(struct cros_ec_dev *ec, uint32_t *ver_ptr,
+				 uint32_t *flg_ptr)
+{
+	struct ec_params_lightbar *param;
+	struct ec_response_lightbar *resp;
+	struct cros_ec_command *msg;
+	int ret;
+
+	msg = cros_ec_alloc_lightbar_cmd_msg(ec);
+	if (!msg)
+		return -ENOMEM;
+
+	param = (struct ec_params_lightbar *)msg->data;
+	param->cmd = LIGHTBAR_CMD_VERSION;
+	ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
+	if (ret < 0)
+		goto exit;
+
+	switch (msg->result) {
+	case EC_RES_INVALID_PARAM:
+		/* Pixel had no version command. */
+		if (ver_ptr)
+			*ver_ptr = 0;
+		if (flg_ptr)
+			*flg_ptr = 0;
+		ret = 0;
+		break;
+	case EC_RES_SUCCESS:
+		resp = (struct ec_response_lightbar *)msg->data;
+
+		/* Future devices w/lightbars should implement this command */
+		if (ver_ptr)
+			*ver_ptr = resp->version.num;
+		if (flg_ptr)
+			*flg_ptr = resp->version.flags;
+		ret = 0;
+		break;
+	default:
+		/* Anything else (ie, EC_RES_INVALID_COMMAND) - no lightbar */
+		ret = -ENODEV;
+	}
+exit:
+	kfree(msg);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(cros_ec_get_lightbar_version);
diff --git a/include/linux/platform_data/cros_ec_proto.h b/include/linux/platform_data/cros_ec_proto.h
index 4a415ae851ef..50221254956c 100644
--- a/include/linux/platform_data/cros_ec_proto.h
+++ b/include/linux/platform_data/cros_ec_proto.h
@@ -229,6 +229,10 @@ u32 cros_ec_get_host_event(struct cros_ec_device *ec_dev);
 
 int cros_ec_check_features(struct cros_ec_dev *ec, int feature);
 
+struct cros_ec_command *cros_ec_alloc_lightbar_cmd_msg(struct cros_ec_dev *ec);
+int cros_ec_get_lightbar_version(struct cros_ec_dev *ec, uint32_t *ver_ptr,
+				 uint32_t *flg_ptr);
+
 int cros_ec_get_sensor_count(struct cros_ec_dev *ec);
 
 /**
-- 
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