x86/olpc: Add debugfs interface for EC commands

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.

#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>

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;

}

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);

	}

	register_syscore_ops(&olpc_syscore_ops);

	setup_debugfs();

	return 0;

}