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Subject[PATCH v3 2/2] platform/chrome: wilco_ec: Add USB PowerShare Policy control
Date
USB PowerShare is a policy which affects charging via the special
USB PowerShare port (marked with a small lightning bolt or battery icon)
when in low power states:
- In S0, the port will always provide power.
- In S0ix, if power_share is enabled, then power will be supplied to
the port when on AC or if battery is > 50%. Else no power is supplied.
- In S5, if power_share is enabled, then power will be supplied to
the port when on AC. Else no power is supplied.

v3 changes:
- Drop a silly blank line
- Use val > 1 instead of val != 0 && val != 1
v2 changes:
- Move documentation to Documentation/ABI/testing/sysfs-platform-wilco-ec
- Zero out reserved bytes in requests.

Signed-off-by: Nick Crews <ncrews@chromium.org>
---
.../ABI/testing/sysfs-platform-wilco-ec | 16 ++++
drivers/platform/chrome/wilco_ec/sysfs.c | 92 +++++++++++++++++++
2 files changed, 108 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-platform-wilco-ec b/Documentation/ABI/testing/sysfs-platform-wilco-ec
index e074c203cd32..0c07d5e0b737 100644
--- a/Documentation/ABI/testing/sysfs-platform-wilco-ec
+++ b/Documentation/ABI/testing/sysfs-platform-wilco-ec
@@ -9,3 +9,19 @@ Description:
Input should be parseable by kstrtou8() to 0 or 1.
Output will be either "0\n" or "1\n".

+What: /sys/bus/platform/devices/GOOG000C\:00/usb_power_share
+Date: April 2019
+KernelVersion: 5.2
+Description:
+ Control the USB PowerShare Policy. USB PowerShare is a policy
+ which affects charging via the special USB PowerShare port
+ (marked with a small lightning bolt or battery icon) when in
+ low power states:
+ - In S0, the port will always provide power.
+ - In S0ix, if power_share is enabled, then power will be
+ supplied to the port when on AC or if battery is > 50%.
+ Else no power is supplied.
+ - In S5, if power_share is enabled, then power will be supplied
+ to the port when on AC. Else no power is supplied.
+
+ Input should be either "0" or "1".
diff --git a/drivers/platform/chrome/wilco_ec/sysfs.c b/drivers/platform/chrome/wilco_ec/sysfs.c
index 959b5da2eb16..14e1eee95d42 100644
--- a/drivers/platform/chrome/wilco_ec/sysfs.c
+++ b/drivers/platform/chrome/wilco_ec/sysfs.c
@@ -23,6 +23,26 @@ struct boot_on_ac_request {
u8 reserved7;
} __packed;

+#define CMD_USB_POWER_SHARE 0x39
+
+enum usb_power_share_op {
+ POWER_SHARE_GET = 0,
+ POWER_SHARE_SET = 1,
+};
+
+struct usb_power_share_request {
+ u8 cmd; /* Always CMD_USB_POWER_SHARE */
+ u8 reserved;
+ u8 op; /* One of enum usb_power_share_op */
+ u8 val; /* When setting, either 0 or 1 */
+} __packed;
+
+struct usb_power_share_response {
+ u8 reserved;
+ u8 status; /* Set by EC to 0 on success, other value on failure */
+ u8 val; /* When getting, set by EC to either 0 or 1 */
+} __packed;
+
static ssize_t boot_on_ac_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
@@ -57,8 +77,80 @@ static ssize_t boot_on_ac_store(struct device *dev,

static DEVICE_ATTR_WO(boot_on_ac);

+static int send_usb_power_share(struct wilco_ec_device *ec,
+ struct usb_power_share_request *rq,
+ struct usb_power_share_response *rs)
+{
+ struct wilco_ec_message msg;
+ int ret;
+
+ memset(&msg, 0, sizeof(msg));
+ msg.type = WILCO_EC_MSG_LEGACY;
+ msg.request_data = rq;
+ msg.request_size = sizeof(*rq);
+ msg.response_data = rs;
+ msg.response_size = sizeof(*rs);
+ ret = wilco_ec_mailbox(ec, &msg);
+ if (ret < 0)
+ return ret;
+ if (rs->status)
+ return -EIO;
+
+ return 0;
+}
+
+static ssize_t usb_power_share_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct wilco_ec_device *ec = dev_get_drvdata(dev);
+ struct usb_power_share_request rq;
+ struct usb_power_share_response rs;
+ int ret;
+
+ memset(&rq, 0, sizeof(rq));
+ rq.cmd = CMD_USB_POWER_SHARE;
+ rq.op = POWER_SHARE_GET;
+
+ ret = send_usb_power_share(ec, &rq, &rs);
+ if (ret < 0)
+ return ret;
+
+ return sprintf(buf, "%d\n", rs.val);
+}
+
+static ssize_t usb_power_share_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct wilco_ec_device *ec = dev_get_drvdata(dev);
+ struct usb_power_share_request rq;
+ struct usb_power_share_response rs;
+ int ret;
+ u8 val;
+
+ ret = kstrtou8(buf, 10, &val);
+ if (ret < 0)
+ return ret;
+ if (val > 1)
+ return -EINVAL;
+
+ memset(&rq, 0, sizeof(rq));
+ rq.cmd = CMD_USB_POWER_SHARE;
+ rq.op = POWER_SHARE_SET;
+ rq.val = val;
+
+ ret = send_usb_power_share(ec, &rq, &rs);
+ if (ret < 0)
+ return ret;
+
+ return count;
+}
+
+static DEVICE_ATTR_RW(usb_power_share);
+
static struct attribute *wilco_dev_attrs[] = {
&dev_attr_boot_on_ac.attr,
+ &dev_attr_usb_power_share.attr,
NULL,
};

--
2.20.1
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