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Commit a3c8121b authored by Daniel Drake's avatar Daniel Drake Committed by Ingo Molnar
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x86/olpc: Add debugfs interface for EC commands 



Add a debugfs interface for sending commands to the OLPC
Embedded Controller (EC) and reading the responses.  The EC
provides functionality for machine identification, battery and
AC control, wakeup control, etc.

Having a debugfs interface available is useful for EC
development and debugging.

Based on code by Paul Fox (who also approves of the end result).

Signed-off-by: default avatarDaniel Drake <dsd@laptop.org>
Acked-by: default avatarPaul Fox <pgf@laptop.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andres Salomon <dilinger@queued.net>
Link: http://lkml.kernel.org/r/20120327150740.667D09D401E@zog.reactivated.net


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 90e24014

Documentation/ABI/testing/debugfs-olpc

0 → 100644
+16 −0
Original line number Diff line number Diff line 
What:		/sys/kernel/debug/olpc-ec/cmd

Date:		Dec 2011

KernelVersion:	3.4

Contact:	devel@lists.laptop.org

Description:



A generic interface for executing OLPC Embedded Controller commands and

reading their responses.



To execute a command, write data with the format: CC:N A A A A

CC is the (hex) command, N is the count of expected reply bytes, and A A A A

are optional (hex) arguments.



To read the response (if any), read from the generic node after executing

a command. Hex reply bytes will be returned, *whether or not* they came from

the immediately previous command.

arch/x86/platform/olpc/olpc.c

+97 −0
Original line number Diff line number Diff line
@@ -20,6 +20,8 @@ 
#include <linux/platform_device.h>

#include <linux/of.h>

#include <linux/syscore_ops.h>

#include <linux/debugfs.h>

#include <linux/mutex.h>



#include <asm/geode.h>

#include <asm/setup.h>
@@ -31,6 +33,15 @@ EXPORT_SYMBOL_GPL(olpc_platform_info); 


static DEFINE_SPINLOCK(ec_lock);



/* debugfs interface to EC commands */

#define EC_MAX_CMD_ARGS (5 + 1)	/* cmd byte + 5 args */

#define EC_MAX_CMD_REPLY (8)



static struct dentry *ec_debugfs_dir;

static DEFINE_MUTEX(ec_debugfs_cmd_lock);

static unsigned char ec_debugfs_resp[EC_MAX_CMD_REPLY];

static unsigned int ec_debugfs_resp_bytes;



/* EC event mask to be applied during suspend (defining wakeup sources). */

static u16 ec_wakeup_mask;
@@ -269,6 +280,91 @@ int olpc_ec_sci_query(u16 *sci_value) 
}

EXPORT_SYMBOL_GPL(olpc_ec_sci_query);



static ssize_t ec_debugfs_cmd_write(struct file *file, const char __user *buf,

				    size_t size, loff_t *ppos)

{

	int i, m;

	unsigned char ec_cmd[EC_MAX_CMD_ARGS];

	unsigned int ec_cmd_int[EC_MAX_CMD_ARGS];

	char cmdbuf[64];

	int ec_cmd_bytes;



	mutex_lock(&ec_debugfs_cmd_lock);



	size = simple_write_to_buffer(cmdbuf, sizeof(cmdbuf), ppos, buf, size);



	m = sscanf(cmdbuf, "%x:%u %x %x %x %x %x", &ec_cmd_int[0],

		   &ec_debugfs_resp_bytes,

		   &ec_cmd_int[1], &ec_cmd_int[2], &ec_cmd_int[3],

		   &ec_cmd_int[4], &ec_cmd_int[5]);

	if (m < 2 || ec_debugfs_resp_bytes > EC_MAX_CMD_REPLY) {

		/* reset to prevent overflow on read */

		ec_debugfs_resp_bytes = 0;



		printk(KERN_DEBUG "olpc-ec: bad ec cmd:  "

		       "cmd:response-count [arg1 [arg2 ...]]\n");

		size = -EINVAL;

		goto out;

	}



	/* convert scanf'd ints to char */

	ec_cmd_bytes = m - 2;

	for (i = 0; i <= ec_cmd_bytes; i++)

		ec_cmd[i] = ec_cmd_int[i];



	printk(KERN_DEBUG "olpc-ec: debugfs cmd 0x%02x with %d args "

	       "%02x %02x %02x %02x %02x, want %d returns\n",

	       ec_cmd[0], ec_cmd_bytes, ec_cmd[1], ec_cmd[2], ec_cmd[3],

	       ec_cmd[4], ec_cmd[5], ec_debugfs_resp_bytes);



	olpc_ec_cmd(ec_cmd[0], (ec_cmd_bytes == 0) ? NULL : &ec_cmd[1],

		    ec_cmd_bytes, ec_debugfs_resp, ec_debugfs_resp_bytes);



	printk(KERN_DEBUG "olpc-ec: response "

	       "%02x %02x %02x %02x %02x %02x %02x %02x (%d bytes expected)\n",

	       ec_debugfs_resp[0], ec_debugfs_resp[1], ec_debugfs_resp[2],

	       ec_debugfs_resp[3], ec_debugfs_resp[4], ec_debugfs_resp[5],

	       ec_debugfs_resp[6], ec_debugfs_resp[7], ec_debugfs_resp_bytes);



out:

	mutex_unlock(&ec_debugfs_cmd_lock);

	return size;

}



static ssize_t ec_debugfs_cmd_read(struct file *file, char __user *buf,

				   size_t size, loff_t *ppos)

{

	unsigned int i, r;

	char *rp;

	char respbuf[64];



	mutex_lock(&ec_debugfs_cmd_lock);

	rp = respbuf;

	rp += sprintf(rp, "%02x", ec_debugfs_resp[0]);

	for (i = 1; i < ec_debugfs_resp_bytes; i++)

		rp += sprintf(rp, ", %02x", ec_debugfs_resp[i]);

	mutex_unlock(&ec_debugfs_cmd_lock);

	rp += sprintf(rp, "\n");



	r = rp - respbuf;

	return simple_read_from_buffer(buf, size, ppos, respbuf, r);

}



static const struct file_operations ec_debugfs_genops = {

	.write	 = ec_debugfs_cmd_write,

	.read	 = ec_debugfs_cmd_read,

};



static void setup_debugfs(void)

{

	ec_debugfs_dir = debugfs_create_dir("olpc-ec", 0);

	if (ec_debugfs_dir == ERR_PTR(-ENODEV))

		return;



	debugfs_create_file("cmd", 0600, ec_debugfs_dir, NULL,

			    &ec_debugfs_genops);

}



static int olpc_ec_suspend(void)

{

	return olpc_ec_mask_write(ec_wakeup_mask);
@@ -372,6 +468,7 @@ static int __init olpc_init(void) 
	}



	register_syscore_ops(&olpc_syscore_ops);

	setup_debugfs();



	return 0;

}