ec.c

/*
 *  ec.c - ACPI Embedded Controller Driver (v2.0)
 *
 *  Copyright (C) 2006, 2007 Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>
 *  Copyright (C) 2006 Denis Sadykov <denis.m.sadykov@intel.com>
 *  Copyright (C) 2004 Luming Yu <luming.yu@intel.com>
 *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
 *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or (at
 *  your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful, but
 *  WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 */

/* Uncomment next line to get verbose print outs*/
/* #define DEBUG */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/delay.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/interrupt.h>
#include <linux/list.h>
#include <asm/io.h>
#include <acpi/acpi_bus.h>
#include <acpi/acpi_drivers.h>
#include <acpi/actypes.h>

#define ACPI_EC_CLASS			"embedded_controller"
#define ACPI_EC_DEVICE_NAME		"Embedded Controller"
#define ACPI_EC_FILE_INFO		"info"

#undef PREFIX
#define PREFIX				"ACPI: EC: "

/* EC status register */
#define ACPI_EC_FLAG_OBF	0x01	/* Output buffer full */
#define ACPI_EC_FLAG_IBF	0x02	/* Input buffer full */
#define ACPI_EC_FLAG_BURST	0x10	/* burst mode */
#define ACPI_EC_FLAG_SCI	0x20	/* EC-SCI occurred */

/* EC commands */
enum ec_command {
	ACPI_EC_COMMAND_READ = 0x80,
	ACPI_EC_COMMAND_WRITE = 0x81,
	ACPI_EC_BURST_ENABLE = 0x82,
	ACPI_EC_BURST_DISABLE = 0x83,
	ACPI_EC_COMMAND_QUERY = 0x84,
};

/* EC events */
enum ec_event {
	ACPI_EC_EVENT_OBF_1 = 1,	/* Output buffer full */
	ACPI_EC_EVENT_IBF_0,		/* Input buffer empty */
};

#define ACPI_EC_DELAY		500	/* Wait 500ms max. during EC ops */
#define ACPI_EC_UDELAY_GLK	1000	/* Wait 1ms max. to get global lock */
#define ACPI_EC_UDELAY		100	/* Wait 100us before polling EC again */

enum {
	EC_FLAGS_WAIT_GPE = 0,		/* Don't check status until GPE arrives */
	EC_FLAGS_QUERY_PENDING,		/* Query is pending */
	EC_FLAGS_GPE_MODE,		/* Expect GPE to be sent for status change */
	EC_FLAGS_NO_GPE,		/* Don't use GPE mode */
	EC_FLAGS_RESCHEDULE_POLL	/* Re-schedule poll */
};

/* If we find an EC via the ECDT, we need to keep a ptr to its context */
/* External interfaces use first EC only, so remember */
typedef int (*acpi_ec_query_func) (void *data);

struct acpi_ec_query_handler {
	struct list_head node;
	acpi_ec_query_func func;
	acpi_handle handle;
	void *data;
	u8 query_bit;
};

static struct acpi_ec {
	acpi_handle handle;
	unsigned long gpe;
	unsigned long command_addr;
	unsigned long data_addr;
	unsigned long global_lock;
	unsigned long flags;
	struct mutex lock;
	wait_queue_head_t wait;
	struct list_head list;
	struct delayed_work work;
	atomic_t irq_count;
	u8 handlers_installed;
} *boot_ec, *first_ec;

/* --------------------------------------------------------------------------
                             Transaction Management
   -------------------------------------------------------------------------- */

static inline u8 acpi_ec_read_status(struct acpi_ec *ec)
{
	u8 x = inb(ec->command_addr);
	pr_debug(PREFIX "---> status = 0x%2.2x\n", x);
	return x;
}

static inline u8 acpi_ec_read_data(struct acpi_ec *ec)
{
	u8 x = inb(ec->data_addr);
	pr_debug(PREFIX "---> data = 0x%2.2x\n", x);
	return inb(ec->data_addr);
}

static inline void acpi_ec_write_cmd(struct acpi_ec *ec, u8 command)
{
	pr_debug(PREFIX "<--- command = 0x%2.2x\n", command);
	outb(command, ec->command_addr);
}

static inline void acpi_ec_write_data(struct acpi_ec *ec, u8 data)
{
	pr_debug(PREFIX "<--- data = 0x%2.2x\n", data);
	outb(data, ec->data_addr);
}

static inline int acpi_ec_check_status(struct acpi_ec *ec, enum ec_event event)
{
	if (test_bit(EC_FLAGS_WAIT_GPE, &ec->flags))
		return 0;
	if (event == ACPI_EC_EVENT_OBF_1) {
		if (acpi_ec_read_status(ec) & ACPI_EC_FLAG_OBF)
			return 1;
	} else if (event == ACPI_EC_EVENT_IBF_0) {
		if (!(acpi_ec_read_status(ec) & ACPI_EC_FLAG_IBF))
			return 1;
	}

	return 0;
}

static void ec_schedule_ec_poll(struct acpi_ec *ec)
{
	if (test_bit(EC_FLAGS_RESCHEDULE_POLL, &ec->flags))
		schedule_delayed_work(&ec->work,
				      msecs_to_jiffies(ACPI_EC_DELAY));
}

static void ec_switch_to_poll_mode(struct acpi_ec *ec)
{
	set_bit(EC_FLAGS_NO_GPE, &ec->flags);
	clear_bit(EC_FLAGS_GPE_MODE, &ec->flags);
	acpi_disable_gpe(NULL, ec->gpe, ACPI_NOT_ISR);
	set_bit(EC_FLAGS_RESCHEDULE_POLL, &ec->flags);
}

static int acpi_ec_wait(struct acpi_ec *ec, enum ec_event event, int force_poll)
{
	atomic_set(&ec->irq_count, 0);
	if (likely(test_bit(EC_FLAGS_GPE_MODE, &ec->flags)) &&
	    likely(!force_poll)) {
		if (wait_event_timeout(ec->wait, acpi_ec_check_status(ec, event),
				       msecs_to_jiffies(ACPI_EC_DELAY)))
			return 0;
		clear_bit(EC_FLAGS_WAIT_GPE, &ec->flags);
		if (acpi_ec_check_status(ec, event)) {
			/* missing GPEs, switch back to poll mode */
			if (printk_ratelimit())
				pr_info(PREFIX "missing confirmations, "
						"switch off interrupt mode.\n");
			ec_switch_to_poll_mode(ec);
			ec_schedule_ec_poll(ec);
			return 0;
		}
	} else {
		unsigned long delay = jiffies + msecs_to_jiffies(ACPI_EC_DELAY);
		clear_bit(EC_FLAGS_WAIT_GPE, &ec->flags);
		while (time_before(jiffies, delay)) {
			if (acpi_ec_check_status(ec, event))
				return 0;
			msleep(1);
		}
	}
	pr_err(PREFIX "acpi_ec_wait timeout, status = 0x%2.2x, event = %s\n",