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platform/x86: apple-gmux: add debugfs interface

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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 <hdegoede@redhat.com>
Signed-off-by: Orlando Chamberlain <orlandoch.dev@gmail.com>
Link: https://lore.kernel.org/r/20230303112842.3094-5-orlandoch.dev@gmail.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
This commit is contained in:
Orlando Chamberlain 2023-03-03 22:28:43 +11:00 committed by Hans de Goede
parent 0c18184de9
commit f863fac1b1
1 changed files with 82 additions and 0 deletions
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82
drivers/platform/x86/apple-gmux.c
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@ -22,6 +22,7 @@
#include <linux/delay.h>
#include <linux/pci.h>
#include <linux/vga_switcheroo.h>
#include <linux/debugfs.h>
#include <asm/io.h>
/**
@ -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) {