[v3,6/7] i2c: ChromeOS EC tunnel driver

Message ID	1398879850-9111-7-git-send-email-dianders@chromium.org (mailing list archive)
State	Not Applicable, archived
Headers	show Return-Path: <linux-samsung-soc-owner@kernel.org> From: Doug Anderson <dianders@chromium.org> To: lee.jones@linaro.org, swarren@nvidia.com, wsa@the-dreams.de Cc: abrestic@chromium.org, dgreid@chromium.org, olof@lixom.net, sjg@chromium.org, linux-samsung-soc@vger.kernel.org, linux-tegra@vger.kernel.org, Doug Anderson <dianders@chromium.org>, Vincent Palatin <vpalatin@chromium.org>, robh+dt@kernel.org, pawel.moll@arm.com, mark.rutland@arm.com, ijc+devicetree@hellion.org.uk, galak@codeaurora.org, rdunlap@infradead.org, sameo@linux.intel.com, jdelvare@suse.de, shane.huang@amd.com, maxime.ripard@free-electrons.com, laurent.pinchart+renesas@ideasonboard.com, u.kleine-koenig@pengutronix.de, bjorn.andersson@sonymobile.com, kevin.strasser@linux.intel.com, linux@prisktech.co.nz, andrew@lunn.ch, andriy.shevchenko@linux.intel.com, schwidefsky@de.ibm.com, matt.porter@linaro.org, ch.naveen@samsung.com, devicetree@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org Subject: [PATCH v3 6/7] i2c: ChromeOS EC tunnel driver Date: Wed, 30 Apr 2014 10:44:09 -0700 Message-Id: <1398879850-9111-7-git-send-email-dianders@chromium.org> In-Reply-To: <1398879850-9111-1-git-send-email-dianders@chromium.org> References: <1398879850-9111-1-git-send-email-dianders@chromium.org> Sender: linux-samsung-soc-owner@vger.kernel.org Precedence: bulk

On Wed, 30 Apr 2014, Doug Anderson wrote: > On ARM Chromebooks we have a few devices that are accessed by both the > AP (the main "Application Processor") and the EC (the Embedded > Controller). These are: > * The battery (sbs-battery). > * The power management unit tps65090. > > On the original Samsung ARM Chromebook these devices were on an I2C > bus that was shared between the AP and the EC and arbitrated using > some extranal GPIOs (see i2c-arb-gpio-challenge). > > The original arbitration scheme worked well enough but had some > downsides: > * It was nonstandard (not using standard I2C multimaster) > * It only worked if the EC-AP communication was I2C > * It was relatively hard to debug problems (hard to tell if i2c issues > were caused by the EC, the AP, or some device on the bus). > > On the HP Chromebook 11 the design was changed to: > * The AP/EC comms were still i2c, but the battery/tps65090 were no > longer on the bus used for AP/EC communication. The battery was > exposed to the AP through a limited i2c tunnel and tps65090 was > exposed to the AP through a custom Linux driver. > > On the Samsung ARM Chromebook 2 the scheme is changed yet again, now: > * The AP/EC comms are now using SPI for faster speeds. > * The EC's i2c bus is exposed to the AP through a full i2c tunnel. > > The upstream "tegra124-venice2" uses the same scheme as the Samsung > ARM Chromebook 2, though it has a different set of components on the > other side of the bus. > > This driver supports the scheme used by the Samsung ARM Chromebook 2. > Future patches to this driver could add support for the battery tunnel > on the HP Chromebook 11 (and perhaps could even be used to access > tps65090 on the HP Chromebook 11 instead of using a special driver, > but I haven't researched that enough). > > Signed-off-by: Vincent Palatin <vpalatin@chromium.org> > Signed-off-by: Simon Glass <sjg@chromium.org> > Signed-off-by: Doug Anderson <dianders@chromium.org> > --- > Changes in v3: > - Separate out packet sizing from packet stuffing. > - Get rid of useless dev_dbg. > - Check command_sendrecv against NULL. > - Don't check np against NULL. > - Get rid of useless error on memory alloc fail. > - Get rid of useless platform_set_drvdata(dev, NULL); > > Changes in v2: > - Update tunnel binding as per swarren > > .../devicetree/bindings/i2c/i2c-cros-ec-tunnel.txt | 39 +++ > drivers/i2c/busses/Kconfig | 9 + > drivers/i2c/busses/Makefile | 1 + > drivers/i2c/busses/i2c-cros-ec-tunnel.c | 318 +++++++++++++++++++++ > drivers/mfd/cros_ec.c | 5 + > 5 files changed, 372 insertions(+) > create mode 100644 Documentation/devicetree/bindings/i2c/i2c-cros-ec-tunnel.txt > create mode 100644 drivers/i2c/busses/i2c-cros-ec-tunnel.c Applied, thanks. > diff --git a/Documentation/devicetree/bindings/i2c/i2c-cros-ec-tunnel.txt b/Documentation/devicetree/bindings/i2c/i2c-cros-ec-tunnel.txt > new file mode 100644 > index 0000000..898f030 > --- /dev/null > +++ b/Documentation/devicetree/bindings/i2c/i2c-cros-ec-tunnel.txt > @@ -0,0 +1,39 @@ > +I2C bus that tunnels through the ChromeOS EC (cros-ec) > +====================================================== > +On some ChromeOS board designs we've got a connection to the EC (embedded > +controller) but no direct connection to some devices on the other side of > +the EC (like a battery and PMIC). To get access to those devices we need > +to tunnel our i2c commands through the EC. > + > +The node for this device should be under a cros-ec node like google,cros-ec-spi > +or google,cros-ec-i2c. > + > + > +Required properties: > +- compatible: google,cros-ec-i2c-tunnel > +- google,remote-bus: The EC bus we'd like to talk to. > + > +Optional child nodes: > +- One node per I2C device connected to the tunnelled I2C bus. > + > + > +Example: > + cros-ec@0 { > + compatible = "google,cros-ec-spi"; > + > + ... > + > + i2c-tunnel { > + compatible = "google,cros-ec-i2c-tunnel"; > + #address-cells = <1>; > + #size-cells = <0>; > + > + google,remote-bus = <0>; > + > + battery: sbs-battery@b { > + compatible = "sbs,sbs-battery"; > + reg = <0xb>; > + sbs,poll-retry-count = <1>; > + }; > + }; > + } > diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig > index c94db1c..9a0a6cc 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 18d18ff..e110ca9 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 0000000..8e7a714 > --- /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 = &params->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"); > diff --git a/drivers/mfd/cros_ec.c b/drivers/mfd/cros_ec.c > index c58ab96..61bc909 100644 > --- a/drivers/mfd/cros_ec.c > +++ b/drivers/mfd/cros_ec.c > @@ -90,6 +90,11 @@ static const struct mfd_cell cros_devs[] = { > .id = 1, > .of_compatible = "google,cros-ec-keyb", > }, > + { > + .name = "cros-ec-i2c-tunnel", > + .id = 2, > + .of_compatible = "google,cros-ec-i2c-tunnel", > + }, > }; > > int cros_ec_register(struct cros_ec_device *ec_dev)

diff --git a/Documentation/devicetree/bindings/i2c/i2c-cros-ec-tunnel.txt b/Documentation/devicetree/bindings/i2c/i2c-cros-ec-tunnel.txt new file mode 100644 index 0000000..898f030 --- /dev/null +++ b/Documentation/devicetree/bindings/i2c/i2c-cros-ec-tunnel.txt @@ -0,0 +1,39 @@ +I2C bus that tunnels through the ChromeOS EC (cros-ec) +====================================================== +On some ChromeOS board designs we've got a connection to the EC (embedded +controller) but no direct connection to some devices on the other side of +the EC (like a battery and PMIC). To get access to those devices we need +to tunnel our i2c commands through the EC. + +The node for this device should be under a cros-ec node like google,cros-ec-spi +or google,cros-ec-i2c. + + +Required properties: +- compatible: google,cros-ec-i2c-tunnel +- google,remote-bus: The EC bus we'd like to talk to. + +Optional child nodes: +- One node per I2C device connected to the tunnelled I2C bus. + + +Example: + cros-ec@0 { + compatible = "google,cros-ec-spi"; + + ... + + i2c-tunnel { + compatible = "google,cros-ec-i2c-tunnel"; + #address-cells = <1>; + #size-cells = <0>; + + google,remote-bus = <0>; + + battery: sbs-battery@b { + compatible = "sbs,sbs-battery"; + reg = <0xb>; + sbs,poll-retry-count = <1>; + }; + }; + } diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig index c94db1c..9a0a6cc 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 18d18ff..e110ca9 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 0000000..8e7a714 --- /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 = &params->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"); diff --git a/drivers/mfd/cros_ec.c b/drivers/mfd/cros_ec.c index c58ab96..61bc909 100644 --- a/drivers/mfd/cros_ec.c +++ b/drivers/mfd/cros_ec.c @@ -90,6 +90,11 @@ static const struct mfd_cell cros_devs[] = { .id = 1, .of_compatible = "google,cros-ec-keyb", }, + { + .name = "cros-ec-i2c-tunnel", + .id = 2, + .of_compatible = "google,cros-ec-i2c-tunnel", + }, }; int cros_ec_register(struct cros_ec_device *ec_dev)

[v3,6/7] i2c: ChromeOS EC tunnel driver

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