Commit f863fac1 authored by Orlando Chamberlain's avatar Orlando Chamberlain Committed by Hans de Goede
Browse files

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: default avatarHans de Goede <hdegoede@redhat.com>
Signed-off-by: default avatarOrlando Chamberlain <orlandoch.dev@gmail.com>
Link: https://lore.kernel.org/r/20230303112842.3094-5-orlandoch.dev@gmail.com


Signed-off-by: default avatarHans de Goede <hdegoede@redhat.com>
parent 0c18184d

drivers/platform/x86/apple-gmux.c

+82 −0
Original line number Diff line number Diff line
@@ -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 @@ static int gmux_probe(struct pnp_dev *pnp, const struct pnp_device_id *id) 
		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) {