[linux-2.6-block.git] / drivers / gpu / drm / drm_dp_i2c_helper.c

/*
 * Copyright © 2009 Keith Packard
 *
 * Permission to use, copy, modify, distribute, and sell this software and its
 * documentation for any purpose is hereby granted without fee, provided that
 * the above copyright notice appear in all copies and that both that copyright
 * notice and this permission notice appear in supporting documentation, and
 * that the name of the copyright holders not be used in advertising or
 * publicity pertaining to distribution of the software without specific,
 * written prior permission.  The copyright holders make no representations
 * about the suitability of this software for any purpose.  It is provided "as
 * is" without express or implied warranty.
 *
 * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
 * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
 * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
 * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
 * OF THIS SOFTWARE.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/i2c.h>
#include "drm_dp_helper.h"
#include "drmP.h"

/* Run a single AUX_CH I2C transaction, writing/reading data as necessary */
static int
i2c_algo_dp_aux_transaction(struct i2c_adapter *adapter, int mode,
			    uint8_t write_byte, uint8_t *read_byte)
{
	struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
	int ret;
	
	ret = (*algo_data->aux_ch)(adapter, mode,
				   write_byte, read_byte);
	return ret;
}

/*
 * I2C over AUX CH
 */

/*
 * Send the address. If the I2C link is running, this 'restarts'
 * the connection with the new address, this is used for doing
 * a write followed by a read (as needed for DDC)
 */
static int
i2c_algo_dp_aux_address(struct i2c_adapter *adapter, u16 address, bool reading)
{
	struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
	int mode = MODE_I2C_START;
	int ret;

	if (reading)
		mode |= MODE_I2C_READ;
	else
		mode |= MODE_I2C_WRITE;
	algo_data->address = address;
	algo_data->running = true;
	ret = i2c_algo_dp_aux_transaction(adapter, mode, 0, NULL);
	return ret;
}

/*
 * Stop the I2C transaction. This closes out the link, sending
 * a bare address packet with the MOT bit turned off
 */
static void
i2c_algo_dp_aux_stop(struct i2c_adapter *adapter, bool reading)
{
	struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
	int mode = MODE_I2C_STOP;

	if (reading)
		mode |= MODE_I2C_READ;
	else
		mode |= MODE_I2C_WRITE;
	if (algo_data->running) {
		(void) i2c_algo_dp_aux_transaction(adapter, mode, 0, NULL);
		algo_data->running = false;
	}
}

/*
 * Write a single byte to the current I2C address, the
 * the I2C link must be running or this returns -EIO
 */
static int
i2c_algo_dp_aux_put_byte(struct i2c_adapter *adapter, u8 byte)
{
	struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
	int ret;

	if (!algo_data->running)
		return -EIO;

	ret = i2c_algo_dp_aux_transaction(adapter, MODE_I2C_WRITE, byte, NULL);
	return ret;
}

/*
 * Read a single byte from the current I2C address, the
 * I2C link must be running or this returns -EIO
 */
static int
i2c_algo_dp_aux_get_byte(struct i2c_adapter *adapter, u8 *byte_ret)
{
	struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
	int ret;

	if (!algo_data->running)
		return -EIO;

	ret = i2c_algo_dp_aux_transaction(adapter, MODE_I2C_READ, 0, byte_ret);
	return ret;
}

static int
i2c_algo_dp_aux_xfer(struct i2c_adapter *adapter,
		     struct i2c_msg *msgs,
		     int num)
{
	int ret = 0;
	bool reading = false;
	int m;
	int b;

	for (m = 0; m < num; m++) {
		u16 len = msgs[m].len;
		u8 *buf = msgs[m].buf;
		reading = (msgs[m].flags & I2C_M_RD) != 0;
		ret = i2c_algo_dp_aux_address(adapter, msgs[m].addr, reading);
		if (ret < 0)
			break;
		if (reading) {
			for (b = 0; b < len; b++) {
				ret = i2c_algo_dp_aux_get_byte(adapter, &buf[b]);
				if (ret < 0)
					break;
			}
		} else {
			for (b = 0; b < len; b++) {
				ret = i2c_algo_dp_aux_put_byte(adapter, buf[b]);
				if (ret < 0)
					break;
			}
		}
		if (ret < 0)
			break;
	}
	if (ret >= 0)
		ret = num;
	i2c_algo_dp_aux_stop(adapter, reading);
	DRM_DEBUG_KMS("dp_aux_xfer return %d\n", ret);
	return ret;
}

static u32
i2c_algo_dp_aux_functionality(struct i2c_adapter *adapter)
{
	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
	       I2C_FUNC_SMBUS_READ_BLOCK_DATA |
	       I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
	       I2C_FUNC_10BIT_ADDR;
}

static const struct i2c_algorithm i2c_dp_aux_algo = {
	.master_xfer	= i2c_algo_dp_aux_xfer,
	.functionality	= i2c_algo_dp_aux_functionality,
};

static void
i2c_dp_aux_reset_bus(struct i2c_adapter *adapter)
{
	(void) i2c_algo_dp_aux_address(adapter, 0, false);
	(void) i2c_algo_dp_aux_stop(adapter, false);
					   
}

static int
i2c_dp_aux_prepare_bus(struct i2c_adapter *adapter)
{
	adapter->algo = &i2c_dp_aux_algo;
	adapter->retries = 3;
	i2c_dp_aux_reset_bus(adapter);
	return 0;
}

int
i2c_dp_aux_add_bus(struct i2c_adapter *adapter)
{
	int error;
	
	error = i2c_dp_aux_prepare_bus(adapter);
	if (error)
		return error;
	error = i2c_add_adapter(adapter);
	return error;
}
EXPORT_SYMBOL(i2c_dp_aux_add_bus);
Commit	Line	Data
a4fc5ed6 KP	1	/*
	2	* Copyright © 2009 Keith Packard
	3	*
	4	* Permission to use, copy, modify, distribute, and sell this software and its
	5	* documentation for any purpose is hereby granted without fee, provided that
	6	* the above copyright notice appear in all copies and that both that copyright
	7	* notice and this permission notice appear in supporting documentation, and
	8	* that the name of the copyright holders not be used in advertising or
	9	* publicity pertaining to distribution of the software without specific,
	10	* written prior permission. The copyright holders make no representations
	11	* about the suitability of this software for any purpose. It is provided "as
	12	* is" without express or implied warranty.
	13	*
	14	* THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
	15	* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
	16	* EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
	17	* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
	18	* DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
	19	* TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
	20	* OF THIS SOFTWARE.
	21	*/
	22
	23	#include <linux/kernel.h>
	24	#include <linux/module.h>
	25	#include <linux/delay.h>
a4fc5ed6 KP	26	#include <linux/init.h>
	27	#include <linux/errno.h>
	28	#include <linux/sched.h>
	29	#include <linux/i2c.h>
ab2c0672	30	#include "drm_dp_helper.h"
1ae8c0a5	31	#include "drmP.h"
a4fc5ed6 KP	32
a4fc5ed6 KP	33	/* Run a single AUX_CH I2C transaction, writing/reading data as necessary */
a4fc5ed6 KP	34	static int
	35	i2c_algo_dp_aux_transaction(struct i2c_adapter *adapter, int mode,
	36	uint8_t write_byte, uint8_t *read_byte)
	37	{
	38	struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
a4fc5ed6	39	int ret;
ab2c0672 DA	40
	41	ret = (*algo_data->aux_ch)(adapter, mode,
	42	write_byte, read_byte);
	43	return ret;
a4fc5ed6 KP	44	}
	45
	46	/*
	47	* I2C over AUX CH
	48	*/
	49
	50	/*
	51	* Send the address. If the I2C link is running, this 'restarts'
	52	* the connection with the new address, this is used for doing
	53	* a write followed by a read (as needed for DDC)
	54	*/
	55	static int
	56	i2c_algo_dp_aux_address(struct i2c_adapter *adapter, u16 address, bool reading)
	57	{
	58	struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
	59	int mode = MODE_I2C_START;
	60	int ret;
	61
	62	if (reading)
	63	mode \|= MODE_I2C_READ;
	64	else
	65	mode \|= MODE_I2C_WRITE;
	66	algo_data->address = address;
	67	algo_data->running = true;
	68	ret = i2c_algo_dp_aux_transaction(adapter, mode, 0, NULL);
	69	return ret;
	70	}
	71
	72	/*
	73	* Stop the I2C transaction. This closes out the link, sending
	74	* a bare address packet with the MOT bit turned off
	75	*/
	76	static void
	77	i2c_algo_dp_aux_stop(struct i2c_adapter *adapter, bool reading)
	78	{
	79	struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
	80	int mode = MODE_I2C_STOP;
	81
	82	if (reading)
	83	mode \|= MODE_I2C_READ;
	84	else
	85	mode \|= MODE_I2C_WRITE;
	86	if (algo_data->running) {
	87	(void) i2c_algo_dp_aux_transaction(adapter, mode, 0, NULL);
	88	algo_data->running = false;
	89	}
	90	}
	91
	92	/*
	93	* Write a single byte to the current I2C address, the
	94	* the I2C link must be running or this returns -EIO
	95	*/
	96	static int
	97	i2c_algo_dp_aux_put_byte(struct i2c_adapter *adapter, u8 byte)
	98	{
	99	struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
	100	int ret;
	101
	102	if (!algo_data->running)
	103	return -EIO;
	104
	105	ret = i2c_algo_dp_aux_transaction(adapter, MODE_I2C_WRITE, byte, NULL);
	106	return ret;
	107	}
108
109	/*
110	* Read a single byte from the current I2C address, the
111	* I2C link must be running or this returns -EIO
112	*/
113	static int
114	i2c_algo_dp_aux_get_byte(struct i2c_adapter adapter, u8 byte_ret)
115	{
116	struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
117	int ret;
118
119	if (!algo_data->running)
120	return -EIO;
121
122	ret = i2c_algo_dp_aux_transaction(adapter, MODE_I2C_READ, 0, byte_ret);
123	return ret;
124	}
125
126	static int
127	i2c_algo_dp_aux_xfer(struct i2c_adapter *adapter,
128	struct i2c_msg *msgs,
129	int num)
130	{
131	int ret = 0;
132	bool reading = false;
133	int m;
134	int b;
135
136	for (m = 0; m < num; m++) {
137	u16 len = msgs[m].len;
138	u8 *buf = msgs[m].buf;
139	reading = (msgs[m].flags & I2C_M_RD) != 0;
140	ret = i2c_algo_dp_aux_address(adapter, msgs[m].addr, reading);
141	if (ret < 0)
142	break;
143	if (reading) {
144	for (b = 0; b < len; b++) {
145	ret = i2c_algo_dp_aux_get_byte(adapter, &buf[b]);
146	if (ret < 0)
147	break;
148	}
149	} else {
150	for (b = 0; b < len; b++) {
151	ret = i2c_algo_dp_aux_put_byte(adapter, buf[b]);
152	if (ret < 0)
153	break;
154	}
155	}
156	if (ret < 0)
157	break;
158	}
159	if (ret >= 0)
160	ret = num;
161	i2c_algo_dp_aux_stop(adapter, reading);
28c97730	162	DRM_DEBUG_KMS("dp_aux_xfer return %d\n", ret);
a4fc5ed6 KP	163	return ret;
	164	}
	165
	166	static u32
	167	i2c_algo_dp_aux_functionality(struct i2c_adapter *adapter)
	168	{
	169	return I2C_FUNC_I2C \| I2C_FUNC_SMBUS_EMUL \|
	170	I2C_FUNC_SMBUS_READ_BLOCK_DATA \|
	171	I2C_FUNC_SMBUS_BLOCK_PROC_CALL \|
	172	I2C_FUNC_10BIT_ADDR;
	173	}
	174
	175	static const struct i2c_algorithm i2c_dp_aux_algo = {
	176	.master_xfer = i2c_algo_dp_aux_xfer,
	177	.functionality = i2c_algo_dp_aux_functionality,
	178	};
	179
	180	static void
	181	i2c_dp_aux_reset_bus(struct i2c_adapter *adapter)
	182	{
	183	(void) i2c_algo_dp_aux_address(adapter, 0, false);
	184	(void) i2c_algo_dp_aux_stop(adapter, false);
	185
	186	}
	187
	188	static int
	189	i2c_dp_aux_prepare_bus(struct i2c_adapter *adapter)
	190	{
	191	adapter->algo = &i2c_dp_aux_algo;
	192	adapter->retries = 3;
	193	i2c_dp_aux_reset_bus(adapter);
	194	return 0;
	195	}
	196
	197	int
	198	i2c_dp_aux_add_bus(struct i2c_adapter *adapter)
	199	{
	200	int error;
	201
	202	error = i2c_dp_aux_prepare_bus(adapter);
	203	if (error)
	204	return error;
	205	error = i2c_add_adapter(adapter);
	206	return error;
	207	}
	208	EXPORT_SYMBOL(i2c_dp_aux_add_bus);