418 lines
11 KiB
C
418 lines
11 KiB
C
/*
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* Copyright (C) 2013 Google, Inc
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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*
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* Expose an I2C passthrough to the ChromeOS EC.
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*/
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#include <linux/module.h>
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#include <linux/i2c.h>
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#include <linux/mfd/cros_ec.h>
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#include <linux/mfd/cros_ec_commands.h>
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#include <linux/of_i2c.h>
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#include <linux/platform_device.h>
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#include <linux/slab.h>
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#define I2C_MAX_RETRIES 3
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/**
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* struct ec_i2c_device - Driver data for I2C tunnel
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*
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* @dev: Device node
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* @adap: I2C adapter
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* @ec: Pointer to EC device
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* @remote_bus: The EC bus number we tunnel to on the other side.
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* @request_buf: Buffer for transmitting data; we expect most transfers to fit.
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* @response_buf: Buffer for receiving data; we expect most transfers to fit.
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*/
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struct ec_i2c_device {
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struct device *dev;
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struct i2c_adapter adap;
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struct cros_ec_device *ec;
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u16 remote_bus;
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u8 request_buf[256];
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u8 response_buf[256];
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};
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#define CHECK_I2C_WR(num, length) \
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(((msgs[num].flags & I2C_M_RD) == 0) && (msgs[num].len == length))
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#define CHECK_I2C_RD(num, length) \
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((msgs[num].flags & I2C_M_RD) && (msgs[num].len == length))
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/* Standard I2C address for smart batteries */
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#define SBS_I2C_ADDR 0xB
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static int ec_i2c_forward_msg(struct ec_i2c_device *bus, int cmd,
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struct i2c_msg *outmsg, struct i2c_msg *inmsg)
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{
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struct cros_ec_command msg;
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msg.version = 0;
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msg.command = cmd;
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msg.outdata = outmsg ? outmsg->buf : NULL;
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msg.outsize = outmsg ? outmsg->len : 0;
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msg.indata = inmsg ? inmsg->buf : NULL;
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msg.insize = inmsg ? inmsg->len : 0;
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return bus->ec->cmd_xfer(bus->ec, &msg);
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}
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static int ec_i2c_limited_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
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int num)
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{
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struct ec_i2c_device *bus = adap->algo_data;
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if (!num || (msgs[0].addr != SBS_I2C_ADDR))
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return -ENODEV;
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/* Battery device probing */
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if ((num == 1) && (msgs[0].len == 0)) {
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uint8_t dummy[] = { 0x0d, 0 };
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struct i2c_msg otmp = { .buf = dummy, .len = 1 };
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struct i2c_msg itmp = { .buf = dummy, .len = 2 };
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return ec_i2c_forward_msg(bus, EC_CMD_SB_READ_WORD,
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&otmp, &itmp);
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}
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/* Read a word-sized register */
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if ((num == 1) && CHECK_I2C_WR(0, 3))
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return ec_i2c_forward_msg(bus, EC_CMD_SB_WRITE_WORD,
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&msgs[0], NULL);
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/* Write a word-sized register */
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if ((num == 2) && CHECK_I2C_WR(0, 1) && CHECK_I2C_RD(1, 2))
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return ec_i2c_forward_msg(bus, EC_CMD_SB_READ_WORD,
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&msgs[0], &msgs[1]);
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/* Retrieve string data length */
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if ((num == 2) && CHECK_I2C_WR(0, 1) && CHECK_I2C_RD(1, 1)) {
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msgs[1].buf[0] = I2C_SMBUS_BLOCK_MAX;
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return 0;
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}
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/* Read string data */
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if ((num == 2) && CHECK_I2C_WR(0, 1) &&
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CHECK_I2C_RD(1, I2C_SMBUS_BLOCK_MAX)) {
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char tmpblock[I2C_SMBUS_BLOCK_MAX + 1];
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struct i2c_msg tmpmsg = { .buf = tmpblock,
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.len = I2C_SMBUS_BLOCK_MAX };
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int ret;
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ret = ec_i2c_forward_msg(bus, EC_CMD_SB_READ_BLOCK,
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&msgs[0], &tmpmsg);
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tmpblock[I2C_SMBUS_BLOCK_MAX] = 0;
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/* real string length */
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msgs[1].buf[0] = strlen(tmpblock);
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strlcpy(&msgs[1].buf[1], tmpblock, msgs[1].len);
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return ret;
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}
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return -EIO;
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}
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/**
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* ec_i2c_construct_message - construct a message to go to the EC
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*
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* This function effectively stuffs the standard i2c_msg format of Linux into
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* a format that the EC understands.
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*
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* @buf: The buffer to fill. Can pass NULL to count how many bytes the message
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* would be.
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* @i2c_msgs: The i2c messages to read.
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* @num: The number of i2c messages.
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* @bus_num: The remote bus number we want to talk to.
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*
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* Returns the number of bytes that the message would take up or a negative
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* error number.
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*/
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static int ec_i2c_construct_message(u8 *buf, const struct i2c_msg i2c_msgs[],
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int num, u16 bus_num)
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{
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struct ec_params_i2c_passthru *params;
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u8 *out_data;
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int i;
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int size;
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size = sizeof(struct ec_params_i2c_passthru);
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size += num * sizeof(struct ec_params_i2c_passthru_msg);
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out_data = buf + size;
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for (i = 0; i < num; i++)
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if (!(i2c_msgs[i].flags & I2C_M_RD))
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size += i2c_msgs[i].len;
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/* If there is no buffer, we can't build the message */
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if (!buf)
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return size;
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params = (struct ec_params_i2c_passthru *)buf;
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params->port = bus_num;
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params->num_msgs = num;
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for (i = 0; i < num; i++) {
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const struct i2c_msg *i2c_msg = &i2c_msgs[i];
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struct ec_params_i2c_passthru_msg *msg = ¶ms->msg[i];
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msg->len = i2c_msg->len;
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msg->addr_flags = i2c_msg->addr;
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if (i2c_msg->flags & I2C_M_TEN)
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msg->addr_flags |= EC_I2C_FLAG_10BIT;
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if (i2c_msg->flags & I2C_M_RD) {
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msg->addr_flags |= EC_I2C_FLAG_READ;
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} else {
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memcpy(out_data, i2c_msg->buf, msg->len);
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out_data += msg->len;
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}
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}
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return size;
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}
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/**
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* ec_i2c_parse_response - Parse a response from the EC
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*
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* We'll take the EC's response and copy it back into msgs.
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*
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* @buf: The buffer to parse. Can pass NULL to count how many bytes we expect
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* the response to be. Otherwise we assume that the right number of
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* bytes are available.
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* @i2c_msgs: The i2c messages to to fill up.
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* @num: The number of i2c messages; will be modified to include the actual
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* number received.
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*
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* Returns the number of response bytes or a negative error number.
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*/
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static int ec_i2c_parse_response(const u8 *buf, struct i2c_msg i2c_msgs[],
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int *num)
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{
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const struct ec_response_i2c_passthru *resp;
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const u8 *in_data;
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int size;
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int i;
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size = sizeof(struct ec_response_i2c_passthru);
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in_data = buf + size;
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for (i = 0; i < *num; i++)
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if (i2c_msgs[i].flags & I2C_M_RD)
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size += i2c_msgs[i].len;
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if (buf == NULL)
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return size;
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resp = (const struct ec_response_i2c_passthru *)buf;
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if (resp->i2c_status & EC_I2C_STATUS_TIMEOUT)
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return -ETIMEDOUT;
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else if (resp->i2c_status & EC_I2C_STATUS_ERROR)
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return -EREMOTEIO;
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/* Other side could send us back fewer messages, but not more */
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if (resp->num_msgs > *num)
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return -EPROTO;
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*num = resp->num_msgs;
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for (i = 0; i < *num; i++) {
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struct i2c_msg *i2c_msg = &i2c_msgs[i];
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if (i2c_msgs[i].flags & I2C_M_RD) {
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memcpy(i2c_msg->buf, in_data, i2c_msg->len);
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in_data += i2c_msg->len;
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}
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}
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return size;
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}
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static int ec_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg i2c_msgs[],
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int num)
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{
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struct ec_i2c_device *bus = adap->algo_data;
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struct device *dev = bus->dev;
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const u16 bus_num = bus->remote_bus;
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int request_len;
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int response_len;
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u8 *request = NULL;
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u8 *response = NULL;
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int result;
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struct cros_ec_command msg;
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request_len = ec_i2c_construct_message(NULL, i2c_msgs, num, bus_num);
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if (request_len < 0) {
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dev_warn(dev, "Error constructing message %d\n", request_len);
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result = request_len;
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goto exit;
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}
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response_len = ec_i2c_parse_response(NULL, i2c_msgs, &num);
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if (response_len < 0) {
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/* Unexpected; no errors should come when NULL response */
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dev_warn(dev, "Error preparing response %d\n", response_len);
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result = response_len;
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goto exit;
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}
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if (request_len <= ARRAY_SIZE(bus->request_buf)) {
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request = bus->request_buf;
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} else {
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request = kzalloc(request_len, GFP_KERNEL);
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if (request == NULL) {
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result = -ENOMEM;
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goto exit;
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}
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}
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if (response_len <= ARRAY_SIZE(bus->response_buf)) {
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response = bus->response_buf;
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} else {
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response = kzalloc(response_len, GFP_KERNEL);
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if (response == NULL) {
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result = -ENOMEM;
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goto exit;
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}
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}
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ec_i2c_construct_message(request, i2c_msgs, num, bus_num);
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msg.version = 0;
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msg.command = EC_CMD_I2C_PASSTHRU;
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msg.outdata = request;
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msg.outsize = request_len;
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msg.indata = response;
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msg.insize = response_len;
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result = cros_ec_cmd_xfer(bus->ec, &msg);
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if (result < 0)
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goto exit;
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/* FIXME: This assumes msg.result == EC_RES_SUCCESS */
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result = ec_i2c_parse_response(response, i2c_msgs, &num);
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if (result < 0)
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goto exit;
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/* Indicate success by saying how many messages were sent */
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result = num;
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exit:
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if (request != bus->request_buf)
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kfree(request);
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if (response != bus->response_buf)
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kfree(response);
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return result;
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}
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static u32 ec_i2c_functionality(struct i2c_adapter *adap)
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{
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return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
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}
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static const struct i2c_algorithm ec_i2c_limited_algorithm = {
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.master_xfer = ec_i2c_limited_xfer,
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.functionality = ec_i2c_functionality,
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};
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static const struct i2c_algorithm ec_i2c_algorithm = {
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.master_xfer = ec_i2c_xfer,
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.functionality = ec_i2c_functionality,
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};
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static int ec_i2c_probe(struct platform_device *pdev)
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{
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struct device_node *np = pdev->dev.of_node;
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struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
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struct device *dev = &pdev->dev;
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struct ec_i2c_device *bus = NULL;
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u32 remote_bus;
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int err;
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dev_dbg(dev, "Probing\n");
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if (!np) {
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dev_err(dev, "no device node\n");
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return -ENOENT;
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}
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bus = devm_kzalloc(dev, sizeof(*bus), GFP_KERNEL);
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if (bus == NULL) {
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dev_err(dev, "cannot allocate bus device\n");
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return -ENOMEM;
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}
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err = of_property_read_u32(np, "google,remote-bus", &remote_bus);
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if (err) {
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dev_err(dev, "Couldn't read remote-bus property\n");
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return err;
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}
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bus->remote_bus = remote_bus;
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bus->ec = ec;
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bus->dev = dev;
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bus->adap.owner = THIS_MODULE;
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strlcpy(bus->adap.name, "cros-ec-i2c-tunnel", sizeof(bus->adap.name));
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bus->adap.algo = &ec_i2c_algorithm;
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bus->adap.algo_data = bus;
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bus->adap.dev.parent = &pdev->dev;
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bus->adap.dev.of_node = np;
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bus->adap.retries = I2C_MAX_RETRIES;
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if (of_find_property(np, "google,limited-passthrough", NULL))
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bus->adap.algo = &ec_i2c_limited_algorithm;
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err = i2c_add_adapter(&bus->adap);
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if (err) {
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dev_err(dev, "cannot register i2c adapter\n");
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return err;
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}
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platform_set_drvdata(pdev, bus);
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dev_dbg(dev, "ChromeOS EC I2C tunnel adapter\n");
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of_i2c_register_devices(&bus->adap);
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return err;
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}
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static int ec_i2c_remove(struct platform_device *dev)
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{
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struct ec_i2c_device *bus = platform_get_drvdata(dev);
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platform_set_drvdata(dev, NULL);
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i2c_del_adapter(&bus->adap);
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return 0;
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}
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static struct platform_driver ec_i2c_tunnel_driver = {
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.probe = ec_i2c_probe,
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.remove = ec_i2c_remove,
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.driver = {
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.name = "cros-ec-i2c-tunnel",
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},
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};
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static int __init ec_i2c_init(void)
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{
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return platform_driver_register(&ec_i2c_tunnel_driver);
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}
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subsys_initcall(ec_i2c_init);
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static void __exit ec_i2c_exit(void)
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{
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platform_driver_unregister(&ec_i2c_tunnel_driver);
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}
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module_exit(ec_i2c_exit);
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("EC I2C tunnel driver");
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MODULE_ALIAS("platform:cros-ec-i2c-tunnel");
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