linux/drivers/media/video/smiapp/smiapp-regs.c

/*
 * drivers/media/video/smiapp/smiapp-regs.c
 *
 * Generic driver for SMIA/SMIA++ compliant camera modules
 *
 * Copyright (C) 2011--2012 Nokia Corporation
 * Contact: Sakari Ailus <sakari.ailus@maxwell.research.nokia.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 *
 * 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., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 *
 */

#include "smiapp-debug.h"

#include <linux/delay.h>
#include <linux/i2c.h>

#include "smiapp-regs.h"

static uint32_t float_to_u32_mul_1000000(struct i2c_client *client,
					 uint32_t phloat)
{
	int32_t exp;
	uint64_t man;

	if (phloat >= 0x80000000) {
		dev_err(&client->dev, "this is a negative number\n");
		return 0;
	}

	if (phloat == 0x7f800000)
		return ~0; /* Inf. */

	if ((phloat & 0x7f800000) == 0x7f800000) {
		dev_err(&client->dev, "NaN or other special number\n");
		return 0;
	}

	/* Valid cases begin here */
	if (phloat == 0)
		return 0; /* Valid zero */

	if (phloat > 0x4f800000)
		return ~0; /* larger than 4294967295 */

	/*
	 * Unbias exponent (note how phloat is now guaranteed to
	 * have 0 in the high bit)
	 */
	exp = ((int32_t)phloat >> 23) - 127;

	/* Extract mantissa, add missing '1' bit and it's in MHz */
	man = ((phloat & 0x7fffff) | 0x800000) * 1000000ULL;

	if (exp < 0)
		man >>= -exp;
	else
		man <<= exp;

	man >>= 23; /* Remove mantissa bias */

	return man & 0xffffffff;
}


/*
 * Read a 8/16/32-bit i2c register.  The value is returned in 'val'.
 * Returns zero if successful, or non-zero otherwise.
 */
int smiapp_read(struct i2c_client *client, u32 reg, u32 *val)
{
	struct i2c_msg msg;
	unsigned char data[4];
	unsigned int len = (u8)(reg >> 16);
	u16 offset = reg;
	int r;

	if (len != SMIA_REG_8BIT && len != SMIA_REG_16BIT
	    && len != SMIA_REG_32BIT)
		return -EINVAL;

	msg.addr = client->addr;
	msg.flags = 0;
	msg.len = 2;
	msg.buf = data;

	/* high byte goes out first */
	data[0] = (u8) (offset >> 8);
	data[1] = (u8) offset;
	r = i2c_transfer(client->adapter, &msg, 1);
	if (r != 1) {
		if (r >= 0)
			r = -EBUSY;
		goto err;
	}

	msg.len = len;
	msg.flags = I2C_M_RD;
	r = i2c_transfer(client->adapter, &msg, 1);
	if (r != 1) {
		if (r >= 0)
			r = -EBUSY;
		goto err;
	}

	*val = 0;
	/* high byte comes first */
	switch (len) {
	case SMIA_REG_32BIT:
		*val = (data[0] << 24) + (data[1] << 16) + (data[2] << 8) +
			data[3];
		break;
	case SMIA_REG_16BIT:
		*val = (data[0] << 8) + data[1];
		break;
	case SMIA_REG_8BIT:
		*val = data[0];
		break;
	default:
		BUG();
	}

	if (reg & SMIA_REG_FLAG_FLOAT)
		*val = float_to_u32_mul_1000000(client, *val);

	return 0;

err:
	dev_err(&client->dev, "read from offset 0x%x error %d\n", offset, r);

	return r;
}

/*
 * Write to a 8/16-bit register.
 * Returns zero if successful, or non-zero otherwise.
 */
int smiapp_write(struct i2c_client *client, u32 reg, u32 val)
{
	struct i2c_msg msg;
	unsigned char data[6];
	unsigned int retries;
	unsigned int flags = reg >> 24;
	unsigned int len = (u8)(reg >> 16);
	u16 offset = reg;
	int r;

	if ((len != SMIA_REG_8BIT && len != SMIA_REG_16BIT &&
	     len != SMIA_REG_32BIT) || flags)
		return -EINVAL;

	msg.addr = client->addr;
	msg.flags = 0; /* Write */
	msg.len = 2 + len;
	msg.buf = data;

	/* high byte goes out first */
	data[0] = (u8) (reg >> 8);
	data[1] = (u8) (reg & 0xff);

	switch (len) {
	case SMIA_REG_8BIT:
		data[2] = val;
		break;
	case SMIA_REG_16BIT:
		data[2] = val >> 8;
		data[3] = val;
		break;
	case SMIA_REG_32BIT:
		data[2] = val >> 24;
		data[3] = val >> 16;
		data[4] = val >> 8;
		data[5] = val;
		break;
	default:
		BUG();
	}

	for (retries = 0; retries < 5; retries++) {
		/*
		 * Due to unknown reason sensor stops responding. This
		 * loop is a temporaty solution until the root cause
		 * is found.
		 */
		r = i2c_transfer(client->adapter, &msg, 1);
		if (r == 1) {
			if (retries)
				dev_err(&client->dev,
					"sensor i2c stall encountered. "
					"retries: %d\n", retries);
			return 0;
		}

		usleep_range(2000, 2000);
	}

	dev_err(&client->dev,
		"wrote 0x%x to offset 0x%x error %d\n", val, offset, r);

	return r;
}