diff options
Diffstat (limited to 'drivers/i2c')
| -rw-r--r-- | drivers/i2c/busses/Kconfig | 9 | ||||
| -rw-r--r-- | drivers/i2c/busses/Makefile | 1 | ||||
| -rw-r--r-- | drivers/i2c/busses/i2c-cros-ec-tunnel.c | 318 |
3 files changed, 328 insertions, 0 deletions
diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig index c94db1c5e353..9a0a6cc7f4ba 100644 --- a/drivers/i2c/busses/Kconfig +++ b/drivers/i2c/busses/Kconfig @@ -993,6 +993,15 @@ config I2C_SIBYTE help Supports the SiByte SOC on-chip I2C interfaces (2 channels). +config I2C_CROS_EC_TUNNEL + tristate "ChromeOS EC tunnel I2C bus" + depends on MFD_CROS_EC + help + If you say yes here you get an I2C bus that will tunnel i2c commands + through to the other side of the ChromeOS EC to the i2c bus + connected there. This will work whatever the interface used to + talk to the EC (SPI, I2C or LPC). + config SCx200_I2C tristate "NatSemi SCx200 I2C using GPIO pins (DEPRECATED)" depends on SCx200_GPIO diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile index 18d18ff9db93..e110ca932918 100644 --- a/drivers/i2c/busses/Makefile +++ b/drivers/i2c/busses/Makefile @@ -95,6 +95,7 @@ obj-$(CONFIG_I2C_VIPERBOARD) += i2c-viperboard.o # Other I2C/SMBus bus drivers obj-$(CONFIG_I2C_ACORN) += i2c-acorn.o obj-$(CONFIG_I2C_BCM_KONA) += i2c-bcm-kona.o +obj-$(CONFIG_I2C_CROS_EC_TUNNEL) += i2c-cros-ec-tunnel.o obj-$(CONFIG_I2C_ELEKTOR) += i2c-elektor.o obj-$(CONFIG_I2C_PCA_ISA) += i2c-pca-isa.o obj-$(CONFIG_I2C_SIBYTE) += i2c-sibyte.o diff --git a/drivers/i2c/busses/i2c-cros-ec-tunnel.c b/drivers/i2c/busses/i2c-cros-ec-tunnel.c new file mode 100644 index 000000000000..8e7a71487bb1 --- /dev/null +++ b/drivers/i2c/busses/i2c-cros-ec-tunnel.c @@ -0,0 +1,318 @@ +/* + * Copyright (C) 2013 Google, Inc + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * Expose an I2C passthrough to the ChromeOS EC. + */ + +#include <linux/module.h> +#include <linux/i2c.h> +#include <linux/mfd/cros_ec.h> +#include <linux/mfd/cros_ec_commands.h> +#include <linux/platform_device.h> +#include <linux/slab.h> + +/** + * struct ec_i2c_device - Driver data for I2C tunnel + * + * @dev: Device node + * @adap: I2C adapter + * @ec: Pointer to EC device + * @remote_bus: The EC bus number we tunnel to on the other side. + * @request_buf: Buffer for transmitting data; we expect most transfers to fit. + * @response_buf: Buffer for receiving data; we expect most transfers to fit. + */ + +struct ec_i2c_device { + struct device *dev; + struct i2c_adapter adap; + struct cros_ec_device *ec; + + u16 remote_bus; + + u8 request_buf[256]; + u8 response_buf[256]; +}; + +/** + * ec_i2c_count_message - Count bytes needed for ec_i2c_construct_message + * + * @i2c_msgs: The i2c messages to read + * @num: The number of i2c messages. + * + * Returns the number of bytes the messages will take up. + */ +static int ec_i2c_count_message(const struct i2c_msg i2c_msgs[], int num) +{ + int i; + int size; + + size = sizeof(struct ec_params_i2c_passthru); + size += num * sizeof(struct ec_params_i2c_passthru_msg); + for (i = 0; i < num; i++) + if (!(i2c_msgs[i].flags & I2C_M_RD)) + size += i2c_msgs[i].len; + + return size; +} + +/** + * ec_i2c_construct_message - construct a message to go to the EC + * + * This function effectively stuffs the standard i2c_msg format of Linux into + * a format that the EC understands. + * + * @buf: The buffer to fill. We assume that the buffer is big enough. + * @i2c_msgs: The i2c messages to read. + * @num: The number of i2c messages. + * @bus_num: The remote bus number we want to talk to. + * + * Returns 0 or a negative error number. + */ +static int ec_i2c_construct_message(u8 *buf, const struct i2c_msg i2c_msgs[], + int num, u16 bus_num) +{ + struct ec_params_i2c_passthru *params; + u8 *out_data; + int i; + + out_data = buf + sizeof(struct ec_params_i2c_passthru) + + num * sizeof(struct ec_params_i2c_passthru_msg); + + params = (struct ec_params_i2c_passthru *)buf; + params->port = bus_num; + params->num_msgs = num; + for (i = 0; i < num; i++) { + const struct i2c_msg *i2c_msg = &i2c_msgs[i]; + struct ec_params_i2c_passthru_msg *msg = ¶ms->msg[i]; + + msg->len = i2c_msg->len; + msg->addr_flags = i2c_msg->addr; + + if (i2c_msg->flags & I2C_M_TEN) + msg->addr_flags |= EC_I2C_FLAG_10BIT; + + if (i2c_msg->flags & I2C_M_RD) { + msg->addr_flags |= EC_I2C_FLAG_READ; + } else { + memcpy(out_data, i2c_msg->buf, msg->len); + out_data += msg->len; + } + } + + return 0; +} + +/** + * ec_i2c_count_response - Count bytes needed for ec_i2c_parse_response + * + * @i2c_msgs: The i2c messages to to fill up. + * @num: The number of i2c messages expected. + * + * Returns the number of response bytes expeced. + */ +static int ec_i2c_count_response(struct i2c_msg i2c_msgs[], int num) +{ + int size; + int i; + + size = sizeof(struct ec_response_i2c_passthru); + for (i = 0; i < num; i++) + if (i2c_msgs[i].flags & I2C_M_RD) + size += i2c_msgs[i].len; + + return size; +} + +/** + * ec_i2c_parse_response - Parse a response from the EC + * + * We'll take the EC's response and copy it back into msgs. + * + * @buf: The buffer to parse. + * @i2c_msgs: The i2c messages to to fill up. + * @num: The number of i2c messages; will be modified to include the actual + * number received. + * + * Returns 0 or a negative error number. + */ +static int ec_i2c_parse_response(const u8 *buf, struct i2c_msg i2c_msgs[], + int *num) +{ + const struct ec_response_i2c_passthru *resp; + const u8 *in_data; + int i; + + in_data = buf + sizeof(struct ec_response_i2c_passthru); + + resp = (const struct ec_response_i2c_passthru *)buf; + if (resp->i2c_status & EC_I2C_STATUS_TIMEOUT) + return -ETIMEDOUT; + else if (resp->i2c_status & EC_I2C_STATUS_ERROR) + return -EREMOTEIO; + + /* Other side could send us back fewer messages, but not more */ + if (resp->num_msgs > *num) + return -EPROTO; + *num = resp->num_msgs; + + for (i = 0; i < *num; i++) { + struct i2c_msg *i2c_msg = &i2c_msgs[i]; + + if (i2c_msgs[i].flags & I2C_M_RD) { + memcpy(i2c_msg->buf, in_data, i2c_msg->len); + in_data += i2c_msg->len; + } + } + + return 0; +} + +static int ec_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg i2c_msgs[], + int num) +{ + struct ec_i2c_device *bus = adap->algo_data; + struct device *dev = bus->dev; + const u16 bus_num = bus->remote_bus; + int request_len; + int response_len; + u8 *request = NULL; + u8 *response = NULL; + int result; + + request_len = ec_i2c_count_message(i2c_msgs, num); + if (request_len < 0) { + dev_warn(dev, "Error constructing message %d\n", request_len); + result = request_len; + goto exit; + } + response_len = ec_i2c_count_response(i2c_msgs, num); + if (response_len < 0) { + /* Unexpected; no errors should come when NULL response */ + dev_warn(dev, "Error preparing response %d\n", response_len); + result = response_len; + goto exit; + } + + if (request_len <= ARRAY_SIZE(bus->request_buf)) { + request = bus->request_buf; + } else { + request = kzalloc(request_len, GFP_KERNEL); + if (request == NULL) { + result = -ENOMEM; + goto exit; + } + } + if (response_len <= ARRAY_SIZE(bus->response_buf)) { + response = bus->response_buf; + } else { + response = kzalloc(response_len, GFP_KERNEL); + if (response == NULL) { + result = -ENOMEM; + goto exit; + } + } + + ec_i2c_construct_message(request, i2c_msgs, num, bus_num); + result = bus->ec->command_sendrecv(bus->ec, EC_CMD_I2C_PASSTHRU, + request, request_len, + response, response_len); + if (result) + goto exit; + + result = ec_i2c_parse_response(response, i2c_msgs, &num); + if (result < 0) + goto exit; + + /* Indicate success by saying how many messages were sent */ + result = num; +exit: + if (request != bus->request_buf) + kfree(request); + if (response != bus->response_buf) + kfree(response); + + return result; +} + +static u32 ec_i2c_functionality(struct i2c_adapter *adap) +{ + return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; +} + +static const struct i2c_algorithm ec_i2c_algorithm = { + .master_xfer = ec_i2c_xfer, + .functionality = ec_i2c_functionality, +}; + +static int ec_i2c_probe(struct platform_device *pdev) +{ + struct device_node *np = pdev->dev.of_node; + struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent); + struct device *dev = &pdev->dev; + struct ec_i2c_device *bus = NULL; + u32 remote_bus; + int err; + + if (!ec->command_sendrecv) { + dev_err(dev, "Missing sendrecv\n"); + return -EINVAL; + } + + bus = devm_kzalloc(dev, sizeof(*bus), GFP_KERNEL); + if (bus == NULL) + return -ENOMEM; + + err = of_property_read_u32(np, "google,remote-bus", &remote_bus); + if (err) { + dev_err(dev, "Couldn't read remote-bus property\n"); + return err; + } + bus->remote_bus = remote_bus; + + bus->ec = ec; + bus->dev = dev; + + bus->adap.owner = THIS_MODULE; + strlcpy(bus->adap.name, "cros-ec-i2c-tunnel", sizeof(bus->adap.name)); + bus->adap.algo = &ec_i2c_algorithm; + bus->adap.algo_data = bus; + bus->adap.dev.parent = &pdev->dev; + bus->adap.dev.of_node = np; + + err = i2c_add_adapter(&bus->adap); + if (err) { + dev_err(dev, "cannot register i2c adapter\n"); + return err; + } + platform_set_drvdata(pdev, bus); + + return err; +} + +static int ec_i2c_remove(struct platform_device *dev) +{ + struct ec_i2c_device *bus = platform_get_drvdata(dev); + + i2c_del_adapter(&bus->adap); + + return 0; +} + +static struct platform_driver ec_i2c_tunnel_driver = { + .probe = ec_i2c_probe, + .remove = ec_i2c_remove, + .driver = { + .name = "cros-ec-i2c-tunnel", + }, +}; + +module_platform_driver(ec_i2c_tunnel_driver); + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("EC I2C tunnel driver"); +MODULE_ALIAS("platform:cros-ec-i2c-tunnel"); |