403 lines
9.4 KiB
C
403 lines
9.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* I2C bus driver for Kontron COM modules
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*
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* Copyright (c) 2010-2013 Kontron Europe GmbH
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* Author: Michael Brunner <michael.brunner@kontron.com>
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*
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* The driver is based on the i2c-ocores driver by Peter Korsgaard.
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*/
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#include <linux/module.h>
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#include <linux/platform_device.h>
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#include <linux/i2c.h>
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#include <linux/delay.h>
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#include <linux/mfd/kempld.h>
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#define KEMPLD_I2C_PRELOW 0x0b
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#define KEMPLD_I2C_PREHIGH 0x0c
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#define KEMPLD_I2C_DATA 0x0e
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#define KEMPLD_I2C_CTRL 0x0d
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#define I2C_CTRL_IEN 0x40
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#define I2C_CTRL_EN 0x80
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#define KEMPLD_I2C_STAT 0x0f
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#define I2C_STAT_IF 0x01
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#define I2C_STAT_TIP 0x02
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#define I2C_STAT_ARBLOST 0x20
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#define I2C_STAT_BUSY 0x40
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#define I2C_STAT_NACK 0x80
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#define KEMPLD_I2C_CMD 0x0f
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#define I2C_CMD_START 0x91
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#define I2C_CMD_STOP 0x41
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#define I2C_CMD_READ 0x21
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#define I2C_CMD_WRITE 0x11
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#define I2C_CMD_READ_ACK 0x21
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#define I2C_CMD_READ_NACK 0x29
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#define I2C_CMD_IACK 0x01
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#define KEMPLD_I2C_FREQ_MAX 2700 /* 2.7 mHz */
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#define KEMPLD_I2C_FREQ_STD 100 /* 100 kHz */
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enum {
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STATE_DONE = 0,
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STATE_INIT,
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STATE_ADDR,
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STATE_ADDR10,
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STATE_START,
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STATE_WRITE,
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STATE_READ,
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STATE_ERROR,
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};
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struct kempld_i2c_data {
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struct device *dev;
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struct kempld_device_data *pld;
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struct i2c_adapter adap;
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struct i2c_msg *msg;
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int pos;
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int nmsgs;
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int state;
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bool was_active;
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};
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static unsigned int bus_frequency = KEMPLD_I2C_FREQ_STD;
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module_param(bus_frequency, uint, 0);
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MODULE_PARM_DESC(bus_frequency, "Set I2C bus frequency in kHz (default="
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__MODULE_STRING(KEMPLD_I2C_FREQ_STD)")");
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static int i2c_bus = -1;
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module_param(i2c_bus, int, 0);
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MODULE_PARM_DESC(i2c_bus, "Set I2C bus number (default=-1 for dynamic assignment)");
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static bool i2c_gpio_mux;
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module_param(i2c_gpio_mux, bool, 0);
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MODULE_PARM_DESC(i2c_gpio_mux, "Enable I2C port on GPIO out (default=false)");
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/*
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* kempld_get_mutex must be called prior to calling this function.
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*/
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static int kempld_i2c_process(struct kempld_i2c_data *i2c)
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{
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struct kempld_device_data *pld = i2c->pld;
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u8 stat = kempld_read8(pld, KEMPLD_I2C_STAT);
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struct i2c_msg *msg = i2c->msg;
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u8 addr;
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/* Ready? */
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if (stat & I2C_STAT_TIP)
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return -EBUSY;
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if (i2c->state == STATE_DONE || i2c->state == STATE_ERROR) {
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/* Stop has been sent */
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kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_IACK);
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if (i2c->state == STATE_ERROR)
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return -EIO;
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return 0;
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}
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/* Error? */
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if (stat & I2C_STAT_ARBLOST) {
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i2c->state = STATE_ERROR;
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kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
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return -EAGAIN;
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}
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if (i2c->state == STATE_INIT) {
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if (stat & I2C_STAT_BUSY)
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return -EBUSY;
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i2c->state = STATE_ADDR;
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}
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if (i2c->state == STATE_ADDR) {
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/* 10 bit address? */
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if (i2c->msg->flags & I2C_M_TEN) {
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addr = 0xf0 | ((i2c->msg->addr >> 7) & 0x6);
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/* Set read bit if necessary */
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addr |= (i2c->msg->flags & I2C_M_RD) ? 1 : 0;
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i2c->state = STATE_ADDR10;
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} else {
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addr = i2c_8bit_addr_from_msg(i2c->msg);
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i2c->state = STATE_START;
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}
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kempld_write8(pld, KEMPLD_I2C_DATA, addr);
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kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_START);
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return 0;
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}
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/* Second part of 10 bit addressing */
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if (i2c->state == STATE_ADDR10) {
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kempld_write8(pld, KEMPLD_I2C_DATA, i2c->msg->addr & 0xff);
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kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_WRITE);
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i2c->state = STATE_START;
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return 0;
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}
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if (i2c->state == STATE_START || i2c->state == STATE_WRITE) {
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i2c->state = (msg->flags & I2C_M_RD) ? STATE_READ : STATE_WRITE;
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if (stat & I2C_STAT_NACK) {
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i2c->state = STATE_ERROR;
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kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
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return -ENXIO;
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}
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} else {
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msg->buf[i2c->pos++] = kempld_read8(pld, KEMPLD_I2C_DATA);
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}
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if (i2c->pos >= msg->len) {
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i2c->nmsgs--;
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i2c->msg++;
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i2c->pos = 0;
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msg = i2c->msg;
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if (i2c->nmsgs) {
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if (!(msg->flags & I2C_M_NOSTART)) {
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i2c->state = STATE_ADDR;
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return 0;
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} else {
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i2c->state = (msg->flags & I2C_M_RD)
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? STATE_READ : STATE_WRITE;
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}
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} else {
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i2c->state = STATE_DONE;
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kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
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return 0;
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}
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}
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if (i2c->state == STATE_READ) {
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kempld_write8(pld, KEMPLD_I2C_CMD, i2c->pos == (msg->len - 1) ?
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I2C_CMD_READ_NACK : I2C_CMD_READ_ACK);
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} else {
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kempld_write8(pld, KEMPLD_I2C_DATA, msg->buf[i2c->pos++]);
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kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_WRITE);
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}
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return 0;
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}
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static int kempld_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
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int num)
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{
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struct kempld_i2c_data *i2c = i2c_get_adapdata(adap);
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struct kempld_device_data *pld = i2c->pld;
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unsigned long timeout = jiffies + HZ;
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int ret;
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i2c->msg = msgs;
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i2c->pos = 0;
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i2c->nmsgs = num;
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i2c->state = STATE_INIT;
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/* Handle the transfer */
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while (time_before(jiffies, timeout)) {
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kempld_get_mutex(pld);
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ret = kempld_i2c_process(i2c);
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kempld_release_mutex(pld);
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if (i2c->state == STATE_DONE || i2c->state == STATE_ERROR)
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return (i2c->state == STATE_DONE) ? num : ret;
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if (ret == 0)
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timeout = jiffies + HZ;
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usleep_range(5, 15);
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}
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i2c->state = STATE_ERROR;
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return -ETIMEDOUT;
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}
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/*
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* kempld_get_mutex must be called prior to calling this function.
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*/
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static void kempld_i2c_device_init(struct kempld_i2c_data *i2c)
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{
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struct kempld_device_data *pld = i2c->pld;
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u16 prescale_corr;
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long prescale;
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u8 ctrl;
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u8 stat;
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u8 cfg;
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/* Make sure the device is disabled */
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ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
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ctrl &= ~(I2C_CTRL_EN | I2C_CTRL_IEN);
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kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
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if (bus_frequency > KEMPLD_I2C_FREQ_MAX)
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bus_frequency = KEMPLD_I2C_FREQ_MAX;
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if (pld->info.spec_major == 1)
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prescale = pld->pld_clock / (bus_frequency * 5) - 1000;
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else
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prescale = pld->pld_clock / (bus_frequency * 4) - 3000;
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if (prescale < 0)
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prescale = 0;
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/* Round to the best matching value */
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prescale_corr = prescale / 1000;
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if (prescale % 1000 >= 500)
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prescale_corr++;
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kempld_write8(pld, KEMPLD_I2C_PRELOW, prescale_corr & 0xff);
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kempld_write8(pld, KEMPLD_I2C_PREHIGH, prescale_corr >> 8);
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/* Activate I2C bus output on GPIO pins */
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cfg = kempld_read8(pld, KEMPLD_CFG);
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if (i2c_gpio_mux)
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cfg |= KEMPLD_CFG_GPIO_I2C_MUX;
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else
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cfg &= ~KEMPLD_CFG_GPIO_I2C_MUX;
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kempld_write8(pld, KEMPLD_CFG, cfg);
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/* Enable the device */
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kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_IACK);
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ctrl |= I2C_CTRL_EN;
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kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
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stat = kempld_read8(pld, KEMPLD_I2C_STAT);
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if (stat & I2C_STAT_BUSY)
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kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
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}
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static u32 kempld_i2c_func(struct i2c_adapter *adap)
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{
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return I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR | I2C_FUNC_SMBUS_EMUL;
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}
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static const struct i2c_algorithm kempld_i2c_algorithm = {
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.master_xfer = kempld_i2c_xfer,
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.functionality = kempld_i2c_func,
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};
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static const struct i2c_adapter kempld_i2c_adapter = {
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.owner = THIS_MODULE,
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.name = "i2c-kempld",
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.class = I2C_CLASS_HWMON | I2C_CLASS_SPD |
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I2C_CLASS_DEPRECATED,
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.algo = &kempld_i2c_algorithm,
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};
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static int kempld_i2c_probe(struct platform_device *pdev)
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{
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struct kempld_device_data *pld = dev_get_drvdata(pdev->dev.parent);
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struct kempld_i2c_data *i2c;
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int ret;
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u8 ctrl;
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i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);
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if (!i2c)
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return -ENOMEM;
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i2c->pld = pld;
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i2c->dev = &pdev->dev;
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i2c->adap = kempld_i2c_adapter;
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i2c->adap.dev.parent = i2c->dev;
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ACPI_COMPANION_SET(&i2c->adap.dev, ACPI_COMPANION(&pdev->dev));
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i2c_set_adapdata(&i2c->adap, i2c);
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platform_set_drvdata(pdev, i2c);
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kempld_get_mutex(pld);
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ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
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if (ctrl & I2C_CTRL_EN)
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i2c->was_active = true;
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kempld_i2c_device_init(i2c);
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kempld_release_mutex(pld);
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/* Add I2C adapter to I2C tree */
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if (i2c_bus >= -1)
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i2c->adap.nr = i2c_bus;
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ret = i2c_add_numbered_adapter(&i2c->adap);
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if (ret)
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return ret;
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dev_info(i2c->dev, "I2C bus initialized at %dkHz\n",
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bus_frequency);
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return 0;
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}
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static int kempld_i2c_remove(struct platform_device *pdev)
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{
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struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);
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struct kempld_device_data *pld = i2c->pld;
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u8 ctrl;
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kempld_get_mutex(pld);
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/*
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* Disable I2C logic if it was not activated before the
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* driver loaded
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*/
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if (!i2c->was_active) {
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ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
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ctrl &= ~I2C_CTRL_EN;
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kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
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}
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kempld_release_mutex(pld);
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i2c_del_adapter(&i2c->adap);
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return 0;
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}
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#ifdef CONFIG_PM
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static int kempld_i2c_suspend(struct platform_device *pdev, pm_message_t state)
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{
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struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);
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struct kempld_device_data *pld = i2c->pld;
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u8 ctrl;
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kempld_get_mutex(pld);
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ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
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ctrl &= ~I2C_CTRL_EN;
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kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
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kempld_release_mutex(pld);
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return 0;
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}
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static int kempld_i2c_resume(struct platform_device *pdev)
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{
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struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);
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struct kempld_device_data *pld = i2c->pld;
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kempld_get_mutex(pld);
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kempld_i2c_device_init(i2c);
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kempld_release_mutex(pld);
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return 0;
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}
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#else
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#define kempld_i2c_suspend NULL
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#define kempld_i2c_resume NULL
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#endif
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static struct platform_driver kempld_i2c_driver = {
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.driver = {
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.name = "kempld-i2c",
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},
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.probe = kempld_i2c_probe,
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.remove = kempld_i2c_remove,
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.suspend = kempld_i2c_suspend,
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.resume = kempld_i2c_resume,
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};
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module_platform_driver(kempld_i2c_driver);
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MODULE_DESCRIPTION("KEM PLD I2C Driver");
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MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("platform:kempld_i2c");
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