On Fri, 02 Jan 2015, Javier Martinez Canillas wrote:
> From: Bill Richardson <wfrichar@xxxxxxxxxxxx>
>
> This adds the LPC interface to the Chrome OS EC. Like the
> I2C and SPI drivers, this allows userspace access to the EC.
I'm fairly certain that this is _not_ an MFD device. Please locate it
to the proper subsystem (input?).
> Signed-off-by: Bill Richardson <wfrichar@xxxxxxxxxxxx>
> Signed-off-by: Javier Martinez Canillas <javier.martinez@xxxxxxxxxxxxxxx>
> ---
>
> 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");
--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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