@@ -515,6 +515,16 @@ config VEXPRESS_SYSCFG
bus. System Configuration interface is one of the possible means
of generating transactions on this bus.
+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.
+
source "drivers/misc/c2port/Kconfig"
source "drivers/misc/eeprom/Kconfig"
source "drivers/misc/cb710/Kconfig"
@@ -55,4 +55,5 @@ obj-y += mic/
obj-$(CONFIG_GENWQE) += genwqe/
obj-$(CONFIG_ECHO) += echo/
obj-$(CONFIG_VEXPRESS_SYSCFG) += vexpress-syscfg.o
+obj-$(CONFIG_CROS_EC_LPC) += cros_ec_lpc.o
obj-$(CONFIG_CXL_BASE) += cxl/
new file mode 100644
@@ -0,0 +1,291 @@
+/*
+ * 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/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 platform_driver cros_ec_lpc_driver = {
+ .driver = {
+ .name = DRV_NAME,
+ .owner = THIS_MODULE,
+ },
+ .probe = cros_ec_lpc_probe,
+ .remove = cros_ec_lpc_remove,
+};
+
+static void do_nothing(struct device *dev)
+{
+ /* not a physical device */
+}
+
+static struct platform_device cros_ec_lpc_device = {
+ .name = DRV_NAME,
+ .dev = {
+ .release = do_nothing,
+ },
+};
+
+static int __init cros_ec_lpc_init(void)
+{
+ int ret;
+
+ /* Register the driver */
+ ret = platform_driver_register(&cros_ec_lpc_driver);
+ if (ret < 0) {
+ pr_warn(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 < 0) {
+ pr_warn(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");