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400 lines
9.3 KiB
400 lines
9.3 KiB
// 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 <[email protected]> |
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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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.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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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 <[email protected]>"); |
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MODULE_LICENSE("GPL"); |
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MODULE_ALIAS("platform:kempld_i2c");
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