[PATCH RESEND v2 3/7] mfd: cros_ec: Add cros_ec_lpc driver for x86 devices

[Javier Martinez Canillas <javier.martinez@collabora.co.uk>]

From: Bill Richardson <wfrichar@chromium.org>

This adds the LPC interface to the Chrome OS EC. Like the
I2C and SPI drivers, this allows userspace access to the EC.

Signed-off-by: Bill Richardson <wfrichar@chromium.org>
Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
---

Changes since v1: None, new patch.

 drivers/mfd/Kconfig       |  10 ++
 drivers/mfd/Makefile      |   1 +
 drivers/mfd/cros_ec_lpc.c | 305 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 316 insertions(+)
 create mode 100644 drivers/mfd/cros_ec_lpc.c

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 2e6b731..7563786 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -110,6 +110,16 @@ config MFD_CROS_EC_I2C
 	  a checksum. Failing accesses will be retried three times to
 	  improve reliability.
 
+config MFD_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.
+
 config MFD_CROS_EC_SPI
 	tristate "ChromeOS Embedded Controller (SPI)"
 	depends on MFD_CROS_EC && SPI && OF
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index 53467e2..94c1516 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -11,6 +11,7 @@ obj-$(CONFIG_MFD_ASIC3)		+= asic3.o tmio_core.o
 obj-$(CONFIG_MFD_BCM590XX)	+= bcm590xx.o
 obj-$(CONFIG_MFD_CROS_EC)	+= cros_ec.o
 obj-$(CONFIG_MFD_CROS_EC_I2C)	+= cros_ec_i2c.o
+obj-$(CONFIG_MFD_CROS_EC_LPC)	+= cros_ec_lpc.o
 obj-$(CONFIG_MFD_CROS_EC_SPI)	+= cros_ec_spi.o
 
 rtsx_pci-objs			:= rtsx_pcr.o rtsx_gops.o rts5209.o rts5229.o rtl8411.o rts5227.o rts5249.o
diff --git a/drivers/mfd/cros_ec_lpc.c b/drivers/mfd/cros_ec_lpc.c
new file mode 100644
index 0000000..700e4cf
--- /dev/null
+++ b/drivers/mfd/cros_ec_lpc.c
@@ -0,0 +1,305 @@
+/*
+ * 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 MYNAME "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 err = -ENOTTY;
+
+	if (!request_region(EC_LPC_ADDR_MEMMAP, EC_MEMMAP_SIZE, MYNAME)) {
+		dev_warn(dev, "couldn't reserve memmap region\n");
+		goto failed_memmap;
+	}
+
+	if ((inb(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID) != 'E') ||
+	    (inb(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID + 1) != 'C')) {
+		dev_warn(dev, "EC ID not detected\n");
+		goto failed_ec_probe;
+	}
+
+	if (!request_region(EC_HOST_CMD_REGION0, EC_HOST_CMD_REGION_SIZE,
+			    MYNAME)) {
+		dev_warn(dev, "couldn't reserve region0\n");
+		goto failed_region0;
+	}
+	if (!request_region(EC_HOST_CMD_REGION1, EC_HOST_CMD_REGION_SIZE,
+			    MYNAME)) {
+		dev_warn(dev, "couldn't reserve region1\n");
+		goto failed_region1;
+	}
+
+	ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
+	if (!ec_dev) {
+		err = -ENOMEM;
+		goto failed_ec_dev;
+	}
+
+	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;
+
+	err = cros_ec_register(ec_dev);
+	if (err) {
+		dev_warn(dev, "couldn't register ec_dev\n");
+		goto failed_ec_dev;
+	}
+
+	return 0;
+
+failed_ec_dev:
+	release_region(EC_HOST_CMD_REGION1, EC_HOST_CMD_REGION_SIZE);
+failed_region1:
+	release_region(EC_HOST_CMD_REGION0, EC_HOST_CMD_REGION_SIZE);
+failed_region0:
+failed_ec_probe:
+	release_region(EC_LPC_ADDR_MEMMAP, EC_MEMMAP_SIZE);
+failed_memmap:
+	return err;
+}
+
+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);
+
+	release_region(EC_HOST_CMD_REGION1, EC_HOST_CMD_REGION_SIZE);
+	release_region(EC_HOST_CMD_REGION0, EC_HOST_CMD_REGION_SIZE);
+	release_region(EC_LPC_ADDR_MEMMAP, EC_MEMMAP_SIZE);
+
+	return 0;
+}
+
+static struct platform_driver cros_ec_lpc_driver = {
+	.driver = {
+		.name = MYNAME,
+		.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 = MYNAME,
+	.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(MYNAME ": 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(MYNAME ": 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");
-- 
2.1.3