3 files changed, 332 insertions, 0 deletions

diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig
index 440ed776efd4..6c5f5a1e1175 100644
--- a/drivers/platform/chrome/Kconfig
+++ b/drivers/platform/chrome/Kconfig
@@ -39,4 +39,16 @@ config CHROMEOS_PSTORE
           The module will be called chromeos_pstore.
 
 
+config CROS_EC_LPC
+        tristate "ChromeOS Embedded Controller (LPC)"
+        depends on MFD_CROS_EC
+        help
+          If you say Y here, you get support for talking to the ChromeOS EC
+          over an LPC bus. This uses a simple byte-level protocol with a
+          checksum. This is used for userspace access only. The kernel
+          typically has its own communication methods.
+
+          To compile this driver as a module, choose M here: the
+          module will be called cros_ec_lpc.
+
 endif # CHROMEOS_PLATFORMS
diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
index 2b860ca7450f..03c0260369d9 100644
--- a/drivers/platform/chrome/Makefile
+++ b/drivers/platform/chrome/Makefile
@@ -1,3 +1,4 @@
 
 obj-$(CONFIG_CHROMEOS_LAPTOP)   += chromeos_laptop.o
 obj-$(CONFIG_CHROMEOS_PSTORE)   += chromeos_pstore.o
+obj-$(CONFIG_CROS_EC_LPC)       += cros_ec_lpc.o
diff --git a/drivers/platform/chrome/cros_ec_lpc.c b/drivers/platform/chrome/cros_ec_lpc.c
new file mode 100644
index 000000000000..822fdb36ded9
--- /dev/null
+++ b/drivers/platform/chrome/cros_ec_lpc.c
@@ -0,0 +1,319 @@
+/*
+ * cros_ec_lpc - LPC access to the Chrome OS Embedded Controller
+ *
+ * Copyright (C) 2012-2015 Google, Inc
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * This driver uses the Chrome OS EC byte-level message-based protocol for
+ * communicating the keyboard state (which keys are pressed) from a keyboard EC
+ * to the AP over some bus (such as i2c, lpc, spi).  The EC does debouncing,
+ * but everything else (including deghosting) is done here.  The main
+ * motivation for this is to keep the EC firmware as simple as possible, since
+ * it cannot be easily upgraded and EC flash/IRAM space is relatively
+ * expensive.
+ */
+
+#include <linux/dmi.h>
+#include <linux/delay.h>
+#include <linux/mfd/cros_ec.h>
+#include <linux/mfd/cros_ec_commands.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/printk.h>
+
+#define DRV_NAME "cros_ec_lpc"
+
+static int ec_response_timed_out(void)
+{
+        unsigned long one_second = jiffies + HZ;
+
+        usleep_range(200, 300);
+        do {
+                if (!(inb(EC_LPC_ADDR_HOST_CMD) & EC_LPC_STATUS_BUSY_MASK))
+                        return 0;
+                usleep_range(100, 200);
+        } while (time_before(jiffies, one_second));
+
+        return 1;
+}
+
+static int cros_ec_cmd_xfer_lpc(struct cros_ec_device *ec,
+                                struct cros_ec_command *msg)
+{
+        struct ec_lpc_host_args args;
+        int csum;
+        int i;
+        int ret = 0;
+
+        if (msg->outsize > EC_PROTO2_MAX_PARAM_SIZE ||
+            msg->insize > EC_PROTO2_MAX_PARAM_SIZE) {
+                dev_err(ec->dev,
+                        "invalid buffer sizes (out %d, in %d)\n",
+                        msg->outsize, msg->insize);
+                return -EINVAL;
+        }
+
+        /* Now actually send the command to the EC and get the result */
+        args.flags = EC_HOST_ARGS_FLAG_FROM_HOST;
+        args.command_version = msg->version;
+        args.data_size = msg->outsize;
+
+        /* Initialize checksum */
+        csum = msg->command + args.flags +
+                args.command_version + args.data_size;
+
+        /* Copy data and update checksum */
+        for (i = 0; i < msg->outsize; i++) {
+                outb(msg->outdata[i], EC_LPC_ADDR_HOST_PARAM + i);
+                csum += msg->outdata[i];
+        }
+
+        /* Finalize checksum and write args */
+        args.checksum = csum & 0xFF;
+        outb(args.flags, EC_LPC_ADDR_HOST_ARGS);
+        outb(args.command_version, EC_LPC_ADDR_HOST_ARGS + 1);
+        outb(args.data_size, EC_LPC_ADDR_HOST_ARGS + 2);
+        outb(args.checksum, EC_LPC_ADDR_HOST_ARGS + 3);
+
+        /* Here we go */
+        outb(msg->command, EC_LPC_ADDR_HOST_CMD);
+
+        if (ec_response_timed_out()) {
+                dev_warn(ec->dev, "EC responsed timed out\n");
+                ret = -EIO;
+                goto done;
+        }
+
+        /* Check result */
+        msg->result = inb(EC_LPC_ADDR_HOST_DATA);
+
+        switch (msg->result) {
+        case EC_RES_SUCCESS:
+                break;
+        case EC_RES_IN_PROGRESS:
+                ret = -EAGAIN;
+                dev_dbg(ec->dev, "command 0x%02x in progress\n",
+                        msg->command);
+                goto done;
+        default:
+                dev_dbg(ec->dev, "command 0x%02x returned %d\n",
+                        msg->command, msg->result);
+        }
+
+        /* Read back args */
+        args.flags = inb(EC_LPC_ADDR_HOST_ARGS);
+        args.command_version = inb(EC_LPC_ADDR_HOST_ARGS + 1);
+        args.data_size = inb(EC_LPC_ADDR_HOST_ARGS + 2);
+        args.checksum = inb(EC_LPC_ADDR_HOST_ARGS + 3);
+
+        if (args.data_size > msg->insize) {
+                dev_err(ec->dev,
+                        "packet too long (%d bytes, expected %d)",
+                        args.data_size, msg->insize);
+                ret = -ENOSPC;
+                goto done;
+        }
+
+        /* Start calculating response checksum */
+        csum = msg->command + args.flags +
+                args.command_version + args.data_size;
+
+        /* Read response and update checksum */
+        for (i = 0; i < args.data_size; i++) {
+                msg->indata[i] = inb(EC_LPC_ADDR_HOST_PARAM + i);
+                csum += msg->indata[i];
+        }
+
+        /* Verify checksum */
+        if (args.checksum != (csum & 0xFF)) {
+                dev_err(ec->dev,
+                        "bad packet checksum, expected %02x, got %02x\n",
+                        args.checksum, csum & 0xFF);
+                ret = -EBADMSG;
+                goto done;
+        }
+
+        /* Return actual amount of data received */
+        ret = args.data_size;
+done:
+        return ret;
+}
+
+/* Returns num bytes read, or negative on error. Doesn't need locking. */
+static int cros_ec_lpc_readmem(struct cros_ec_device *ec, unsigned int offset,
+                               unsigned int bytes, void *dest)
+{
+        int i = offset;
+        char *s = dest;
+        int cnt = 0;
+
+        if (offset >= EC_MEMMAP_SIZE - bytes)
+                return -EINVAL;
+
+        /* fixed length */
+        if (bytes) {
+                for (; cnt < bytes; i++, s++, cnt++)
+                        *s = inb(EC_LPC_ADDR_MEMMAP + i);
+                return cnt;
+        }
+
+        /* string */
+        for (; i < EC_MEMMAP_SIZE; i++, s++) {
+                *s = inb(EC_LPC_ADDR_MEMMAP + i);
+                cnt++;
+                if (!*s)
+                        break;
+        }
+
+        return cnt;
+}
+
+static int cros_ec_lpc_probe(struct platform_device *pdev)
+{
+        struct device *dev = &pdev->dev;
+        struct cros_ec_device *ec_dev;
+        int ret;
+
+        if (!devm_request_region(dev, EC_LPC_ADDR_MEMMAP, EC_MEMMAP_SIZE,
+                                 dev_name(dev))) {
+                dev_err(dev, "couldn't reserve memmap region\n");
+                return -EBUSY;
+        }
+
+        if ((inb(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID) != 'E') ||
+            (inb(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID + 1) != 'C')) {
+                dev_err(dev, "EC ID not detected\n");
+                return -ENODEV;
+        }
+
+        if (!devm_request_region(dev, EC_HOST_CMD_REGION0,
+                                 EC_HOST_CMD_REGION_SIZE, dev_name(dev))) {
+                dev_err(dev, "couldn't reserve region0\n");
+                return -EBUSY;
+        }
+        if (!devm_request_region(dev, EC_HOST_CMD_REGION1,
+                                 EC_HOST_CMD_REGION_SIZE, dev_name(dev))) {
+                dev_err(dev, "couldn't reserve region1\n");
+                return -EBUSY;
+        }
+
+        ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
+        if (!ec_dev)
+                return -ENOMEM;
+
+        platform_set_drvdata(pdev, ec_dev);
+        ec_dev->dev = dev;
+        ec_dev->ec_name = pdev->name;
+        ec_dev->phys_name = dev_name(dev);
+        ec_dev->parent = dev;
+        ec_dev->cmd_xfer = cros_ec_cmd_xfer_lpc;
+        ec_dev->cmd_readmem = cros_ec_lpc_readmem;
+
+        ret = cros_ec_register(ec_dev);
+        if (ret) {
+                dev_err(dev, "couldn't register ec_dev (%d)\n", ret);
+                return ret;
+        }
+
+        return 0;
+}
+
+static int cros_ec_lpc_remove(struct platform_device *pdev)
+{
+        struct cros_ec_device *ec_dev;
+
+        ec_dev = platform_get_drvdata(pdev);
+        cros_ec_remove(ec_dev);
+
+        return 0;
+}
+
+static struct dmi_system_id cros_ec_lpc_dmi_table[] __initdata = {
+        {
+                /*
+                 * Today all Chromebooks/boxes ship with Google_* as version and
+                 * coreboot as bios vendor. No other systems with this
+                 * combination are known to date.
+                 */
+                .matches = {
+                        DMI_MATCH(DMI_BIOS_VENDOR, "coreboot"),
+                        DMI_MATCH(DMI_BIOS_VERSION, "Google_"),
+                },
+        },
+        {
+                /* x86-link, the Chromebook Pixel. */
+                .matches = {
+                        DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
+                        DMI_MATCH(DMI_PRODUCT_NAME, "Link"),
+                },
+        },
+        {
+                /* x86-peppy, the Acer C720 Chromebook. */
+                .matches = {
+                        DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
+                        DMI_MATCH(DMI_PRODUCT_NAME, "Peppy"),
+                },
+        },
+        { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(dmi, cros_ec_lpc_dmi_table);
+
+static struct platform_driver cros_ec_lpc_driver = {
+        .driver = {
+                .name = DRV_NAME,
+                .owner = THIS_MODULE,
+        },
+        .probe = cros_ec_lpc_probe,
+        .remove = cros_ec_lpc_remove,
+};
+
+static struct platform_device cros_ec_lpc_device = {
+        .name = DRV_NAME
+};
+
+static int __init cros_ec_lpc_init(void)
+{
+        int ret;
+
+        if (!dmi_check_system(cros_ec_lpc_dmi_table)) {
+                pr_err(DRV_NAME ": unsupported system.\n");
+                return -ENODEV;
+        }
+
+        /* Register the driver */
+        ret = platform_driver_register(&cros_ec_lpc_driver);
+        if (ret) {
+                pr_err(DRV_NAME ": can't register driver: %d\n", ret);
+                return ret;
+        }
+
+        /* Register the device, and it'll get hooked up automatically */
+        ret = platform_device_register(&cros_ec_lpc_device);
+        if (ret) {
+                pr_err(DRV_NAME ": can't register device: %d\n", ret);
+                platform_driver_unregister(&cros_ec_lpc_driver);
+                return ret;
+        }
+
+        return 0;
+}
+
+static void __exit cros_ec_lpc_exit(void)
+{
+        platform_device_unregister(&cros_ec_lpc_device);
+        platform_driver_unregister(&cros_ec_lpc_driver);
+}
+
+module_init(cros_ec_lpc_init);
+module_exit(cros_ec_lpc_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("ChromeOS EC LPC driver");