Allow reading gmux ports from userspace. When the unsafe module
parameter allow_user_writes is true, writing 1 byte
values is also allowed.
For example:
cd /sys/bus/acpi/devices/APP000B:00/physical_node/
echo 4 > gmux_selected_port
cat gmux_selected_port_data | xxd -p
Will show the gmux version information (00000005 in this case)
Signed-off-by: Orlando Chamberlain <orlandoch.dev@xxxxxxxxx>
---
drivers/platform/x86/apple-gmux.c | 129 ++++++++++++++++++++++++++++++
1 file changed, 129 insertions(+)
diff --git a/drivers/platform/x86/apple-gmux.c b/drivers/platform/x86/apple-gmux.c
index c38d6ef0c15a..756059d48393 100644
--- a/drivers/platform/x86/apple-gmux.c
+++ b/drivers/platform/x86/apple-gmux.c
@@ -66,6 +66,11 @@ struct apple_gmux_data {
enum vga_switcheroo_client_id switch_state_external;
enum vga_switcheroo_state power_state;
struct completion powerchange_done;
+
+#ifdef CONFIG_SYSFS
+ /* sysfs data */
+ int selected_port;
+#endif /* CONFIG_SYSFS */
};
static struct apple_gmux_data *apple_gmux_data;
@@ -651,6 +656,121 @@ static void gmux_notify_handler(acpi_handle device, u32 value, void *context)
complete(&gmux_data->powerchange_done);
}
+/**
+ * DOC: Sysfs Interface
+ *
+ * gmux ports can be read from userspace as a sysfs interface. For example:
+ *
+ * # echo 4 > /sys/bus/acpi/devices/APP000B:00/physical_node/gmux_selected_port
+ * # cat /sys/bus/acpi/devices/APP000B:00/physical_node/gmux_selected_port_data | xxd -p
+ * 00000005
+ *
+ * Reads 4 bytes from port 4 (GMUX_PORT_VERSION_MAJOR).
+ *
+ * Single byte writes are also supported, however this must be enabled with the
+ * unsafe allow_user_writes module parameter.
+ *
+ */
+
+#ifdef CONFIG_SYSFS
+
+static bool allow_user_writes;
+module_param_unsafe(allow_user_writes, bool, 0);
+MODULE_PARM_DESC(allow_user_writes, "Allow userspace to write to gmux ports (default: false) (bool)");
+
+static ssize_t gmux_selected_port_store(struct device *dev,
+ struct device_attribute *attr, const char *sysfsbuf, size_t count)
+{
+ struct apple_gmux_data *gmux_data = dev_get_drvdata(dev);
+ u8 port;
+
+ if (kstrtou8(sysfsbuf, 10, &port) < 0)
+ return -EINVAL;
+
+ /* On pio gmux's, make sure the user doesn't access too high of a port. */
+ if ((gmux_data->config == &apple_gmux_pio) &&
+ port > (gmux_data->iolen - 4))
+ return -EINVAL;
+
+ gmux_data->selected_port = port;
+ return count;
+}
+
+static ssize_t gmux_selected_port_show(struct device *dev,
+ struct device_attribute *attr, char *sysfsbuf)
+{
+ struct apple_gmux_data *gmux_data = dev_get_drvdata(dev);
+
+ return sysfs_emit(sysfsbuf, "%d\n", gmux_data->selected_port);
+}
+
+DEVICE_ATTR_RW(gmux_selected_port);
+
+static ssize_t gmux_selected_port_data_store(struct device *dev,
+ struct device_attribute *attr, const char *sysfsbuf, size_t count)
+{
+ struct apple_gmux_data *gmux_data = dev_get_drvdata(dev);
+
+ if (count == 1)
+ gmux_write8(gmux_data, gmux_data->selected_port, *sysfsbuf);
+ else
+ return -EINVAL;
+
+ return count;
+}
+
+static ssize_t gmux_selected_port_data_show(struct device *dev,
+ struct device_attribute *attr, char *sysfsbuf)
+{
+ struct apple_gmux_data *gmux_data = dev_get_drvdata(dev);
+ u32 data;
+
+ data = gmux_read32(gmux_data, gmux_data->selected_port);
+ memcpy(sysfsbuf, &data, sizeof(data));
+
+ return sizeof(data);
+}
+
+struct device_attribute dev_attr_gmux_selected_port_data_rw = __ATTR_RW(gmux_selected_port_data);
+struct device_attribute dev_attr_gmux_selected_port_data_ro = __ATTR_RO(gmux_selected_port_data);
+
+static int gmux_init_sysfs(struct pnp_dev *pnp)
+{
+ int ret;
+
+ ret = device_create_file(&pnp->dev, &dev_attr_gmux_selected_port);
+ if (ret)
+ return ret;
+ if (allow_user_writes)
+ ret = device_create_file(&pnp->dev, &dev_attr_gmux_selected_port_data_rw);
+ else
+ ret = device_create_file(&pnp->dev, &dev_attr_gmux_selected_port_data_ro);
+ if (ret)
+ device_remove_file(&pnp->dev, &dev_attr_gmux_selected_port);
+ return ret;
+}
+
+static void gmux_fini_sysfs(struct pnp_dev *pnp)
+{
+ device_remove_file(&pnp->dev, &dev_attr_gmux_selected_port);
+ if (allow_user_writes)
+ device_remove_file(&pnp->dev, &dev_attr_gmux_selected_port_data_rw);
+ else
+ device_remove_file(&pnp->dev, &dev_attr_gmux_selected_port_data_ro);
+}
+
+#else
+
+static int gmux_init_sysfs(struct pnp_dev *pnp)
+{
+ return 0;
+}
+static void gmux_fini_sysfs(struct pnp_dev *pnp)
+{
+}
+
+#endif /* CONFIG_SYSFS */
+
static int gmux_suspend(struct device *dev)
{
struct pnp_dev *pnp = to_pnp_dev(dev);
@@ -846,8 +966,16 @@ static int gmux_probe(struct pnp_dev *pnp, const struct pnp_device_id *id)
goto err_register_handler;
}
+ ret = gmux_init_sysfs(pnp);
+ if (ret) {
+ pr_err("Failed to register gmux sysfs entries\n");
+ goto err_sysfs;
+ }
+
return 0;
+err_sysfs:
+ vga_switcheroo_unregister_handler();
err_register_handler:
gmux_disable_interrupts(gmux_data);
apple_gmux_data = NULL;
@@ -877,6 +1005,7 @@ static void gmux_remove(struct pnp_dev *pnp)
{
struct apple_gmux_data *gmux_data = pnp_get_drvdata(pnp);
+ gmux_fini_sysfs(pnp);
vga_switcheroo_unregister_handler();
gmux_disable_interrupts(gmux_data);
if (gmux_data->gpe >= 0) {
--
2.39.1
