From f863fac1b15f77fc3c115f5afbd535983bb961a1 Mon Sep 17 00:00:00 2001 From: Orlando Chamberlain Date: Fri, 3 Mar 2023 22:28:43 +1100 Subject: [PATCH] platform/x86: apple-gmux: add debugfs interface Allow reading and writing gmux ports from userspace. For example: echo 4 > /sys/kernel/debug/apple_gmux/selected_port cat /sys/kernel/debug/apple_gmux/selected_port_data | xxd -p Will show the gmux version information (00000005 in this case) Reviewed-by: Hans de Goede Signed-off-by: Orlando Chamberlain Link: https://lore.kernel.org/r/20230303112842.3094-5-orlandoch.dev@gmail.com Signed-off-by: Hans de Goede --- drivers/platform/x86/apple-gmux.c | 82 +++++++++++++++++++++++++++++++ 1 file changed, 82 insertions(+) diff --git a/drivers/platform/x86/apple-gmux.c b/drivers/platform/x86/apple-gmux.c index 59c4ee8109dd..757fd71c900f 100644 --- a/drivers/platform/x86/apple-gmux.c +++ b/drivers/platform/x86/apple-gmux.c @@ -22,6 +22,7 @@ #include #include #include +#include #include /** @@ -73,6 +74,10 @@ struct apple_gmux_data { enum vga_switcheroo_client_id switch_state_external; enum vga_switcheroo_state power_state; struct completion powerchange_done; + + /* debugfs data */ + u8 selected_port; + struct dentry *debug_dentry; }; static struct apple_gmux_data *apple_gmux_data; @@ -670,6 +675,81 @@ static void gmux_notify_handler(acpi_handle device, u32 value, void *context) complete(&gmux_data->powerchange_done); } +/** + * DOC: Debugfs Interface + * + * gmux ports can be accessed from userspace as a debugfs interface. For example: + * + * # echo 4 > /sys/kernel/debug/apple_gmux/selected_port + * # cat /sys/kernel/debug/apple_gmux/selected_port_data | xxd -p + * 00000005 + * + * Reads 4 bytes from port 4 (GMUX_PORT_VERSION_MAJOR). + * + * 1 and 4 byte writes are also allowed. + */ + +static ssize_t gmux_selected_port_data_write(struct file *file, + const char __user *userbuf, size_t count, loff_t *ppos) +{ + struct apple_gmux_data *gmux_data = file->private_data; + int ret; + + if (*ppos) + return -EINVAL; + + if (count == 1) { + u8 data; + + ret = copy_from_user(&data, userbuf, 1); + if (ret) + return ret; + gmux_write8(gmux_data, gmux_data->selected_port, data); + } else if (count == 4) { + u32 data; + + ret = copy_from_user(&data, userbuf, 4); + if (ret) + return ret; + gmux_write32(gmux_data, gmux_data->selected_port, data); + } else + return -EINVAL; + + return count; +} + +static ssize_t gmux_selected_port_data_read(struct file *file, + char __user *userbuf, size_t count, loff_t *ppos) +{ + struct apple_gmux_data *gmux_data = file->private_data; + u32 data; + + data = gmux_read32(gmux_data, gmux_data->selected_port); + + return simple_read_from_buffer(userbuf, count, ppos, &data, sizeof(data)); +} + +static const struct file_operations gmux_port_data_ops = { + .open = simple_open, + .write = gmux_selected_port_data_write, + .read = gmux_selected_port_data_read +}; + +static void gmux_init_debugfs(struct apple_gmux_data *gmux_data) +{ + gmux_data->debug_dentry = debugfs_create_dir(KBUILD_MODNAME, NULL); + + debugfs_create_u8("selected_port", 0644, gmux_data->debug_dentry, + &gmux_data->selected_port); + debugfs_create_file("selected_port_data", 0644, gmux_data->debug_dentry, + gmux_data, &gmux_port_data_ops); +} + +static void gmux_fini_debugfs(struct apple_gmux_data *gmux_data) +{ + debugfs_remove_recursive(gmux_data->debug_dentry); +} + static int gmux_suspend(struct device *dev) { struct pnp_dev *pnp = to_pnp_dev(dev); @@ -870,6 +950,7 @@ get_version: goto err_register_handler; } + gmux_init_debugfs(gmux_data); return 0; err_register_handler: @@ -901,6 +982,7 @@ static void gmux_remove(struct pnp_dev *pnp) { struct apple_gmux_data *gmux_data = pnp_get_drvdata(pnp); + gmux_fini_debugfs(gmux_data); vga_switcheroo_unregister_handler(); gmux_disable_interrupts(gmux_data); if (gmux_data->gpe >= 0) {