Re: [PATCH 05/13] platform/chrome: cros_ec_lpc: Add R/W helpers to LPC protocol variants

[Lee Jones]

On Fri, 17 Mar 2017, Enric Balletbo i Serra wrote:

> From: Shawn Nematbakhsh <shawnn@xxxxxxxxxxxx>
> 
> Call common functions for read / write to prepare support for future
> LPC protocol variants which use different I/O ops than inb / outb.
> 
> Signed-off-by: Shawn Nematbakhsh <shawnn@xxxxxxxxxxxx>
> Signed-off-by: Thierry Escande <thierry.escande@xxxxxxxxxxxxx>
> ---
> Changelog:
>  - v2:
>    -Fixed coding style issues
>    -Updated copyright to year 2016
> 
>  drivers/platform/chrome/Makefile          |  3 +-
>  drivers/platform/chrome/cros_ec_lpc.c     | 88 +++++++++++++------------------
>  drivers/platform/chrome/cros_ec_lpc_reg.c | 64 ++++++++++++++++++++++

>  include/linux/mfd/cros_ec_lpc_reg.h       | 47 +++++++++++++++++

Acked-by: Lee Jones <lee.jones@xxxxxxxxxx>

>  4 files changed, 151 insertions(+), 51 deletions(-)
>  create mode 100644 drivers/platform/chrome/cros_ec_lpc_reg.c
>  create mode 100644 include/linux/mfd/cros_ec_lpc_reg.h
> 
> diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
> index 3870afe..61182fd 100644
> --- a/drivers/platform/chrome/Makefile
> +++ b/drivers/platform/chrome/Makefile
> @@ -5,6 +5,7 @@ cros_ec_devs-objs			:= cros_ec_dev.o cros_ec_sysfs.o \
>  					   cros_ec_lightbar.o cros_ec_vbc.o \
>  					   cros_ec_debugfs.o
>  obj-$(CONFIG_CROS_EC_CHARDEV)		+= cros_ec_devs.o
> -obj-$(CONFIG_CROS_EC_LPC)		+= cros_ec_lpc.o
> +cros_ec_lpcs-objs			:= cros_ec_lpc.o cros_ec_lpc_reg.o
> +obj-$(CONFIG_CROS_EC_LPC)		+= cros_ec_lpcs.o
>  obj-$(CONFIG_CROS_EC_PROTO)		+= cros_ec_proto.o
>  obj-$(CONFIG_CROS_KBD_LED_BACKLIGHT)	+= cros_kbd_led_backlight.o
> diff --git a/drivers/platform/chrome/cros_ec_lpc.c b/drivers/platform/chrome/cros_ec_lpc.c
> index f9a2454..6a782a6 100644
> --- a/drivers/platform/chrome/cros_ec_lpc.c
> +++ b/drivers/platform/chrome/cros_ec_lpc.c
> @@ -26,19 +26,22 @@
>  #include <linux/io.h>
>  #include <linux/mfd/cros_ec.h>
>  #include <linux/mfd/cros_ec_commands.h>
> +#include <linux/mfd/cros_ec_lpc_reg.h>
>  #include <linux/module.h>
>  #include <linux/platform_device.h>
>  #include <linux/printk.h>
>  
> -#define DRV_NAME "cros_ec_lpc"
> +#define DRV_NAME "cros_ec_lpcs"
>  
>  static int ec_response_timed_out(void)
>  {
>  	unsigned long one_second = jiffies + HZ;
> +	u8 data;
>  
>  	usleep_range(200, 300);
>  	do {
> -		if (!(inb(EC_LPC_ADDR_HOST_CMD) & EC_LPC_STATUS_BUSY_MASK))
> +		if (!(cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_CMD, 1, &data) &
> +		    EC_LPC_STATUS_BUSY_MASK))
>  			return 0;
>  		usleep_range(100, 200);
>  	} while (time_before(jiffies, one_second));
> @@ -51,21 +54,20 @@ static int cros_ec_pkt_xfer_lpc(struct cros_ec_device *ec,
>  {
>  	struct ec_host_request *request;
>  	struct ec_host_response response;
> -	u8 sum = 0;
> -	int i;
> +	u8 sum;
>  	int ret = 0;
>  	u8 *dout;
>  
>  	ret = cros_ec_prepare_tx(ec, msg);
>  
>  	/* Write buffer */
> -	for (i = 0; i < ret; i++)
> -		outb(ec->dout[i], EC_LPC_ADDR_HOST_PACKET + i);
> +	cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_PACKET, ret, ec->dout);
>  
>  	request = (struct ec_host_request *)ec->dout;
>  
>  	/* Here we go */
> -	outb(EC_COMMAND_PROTOCOL_3, EC_LPC_ADDR_HOST_CMD);
> +	sum = EC_COMMAND_PROTOCOL_3;
> +	cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_CMD, 1, &sum);
>  
>  	if (ec_response_timed_out()) {
>  		dev_warn(ec->dev, "EC responsed timed out\n");
> @@ -74,17 +76,15 @@ static int cros_ec_pkt_xfer_lpc(struct cros_ec_device *ec,
>  	}
>  
>  	/* Check result */
> -	msg->result = inb(EC_LPC_ADDR_HOST_DATA);
> +	msg->result = cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_DATA, 1, &sum);
>  	ret = cros_ec_check_result(ec, msg);
>  	if (ret)
>  		goto done;
>  
>  	/* Read back response */
>  	dout = (u8 *)&response;
> -	for (i = 0; i < sizeof(response); i++) {
> -		dout[i] = inb(EC_LPC_ADDR_HOST_PACKET + i);
> -		sum += dout[i];
> -	}
> +	sum = cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_PACKET, sizeof(response),
> +				     dout);
>  
>  	msg->result = response.result;
>  
> @@ -97,11 +97,9 @@ static int cros_ec_pkt_xfer_lpc(struct cros_ec_device *ec,
>  	}
>  
>  	/* Read response and process checksum */
> -	for (i = 0; i < response.data_len; i++) {
> -		msg->data[i] =
> -			inb(EC_LPC_ADDR_HOST_PACKET + sizeof(response) + i);
> -		sum += msg->data[i];
> -	}
> +	sum += cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_PACKET +
> +				      sizeof(response), response.data_len,
> +				      msg->data);
>  
>  	if (sum) {
>  		dev_err(ec->dev,
> @@ -121,8 +119,7 @@ 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;
> +	u8 sum;
>  	int ret = 0;
>  
>  	if (msg->outsize > EC_PROTO2_MAX_PARAM_SIZE ||
> @@ -139,24 +136,20 @@ static int cros_ec_cmd_xfer_lpc(struct cros_ec_device *ec,
>  	args.data_size = msg->outsize;
>  
>  	/* Initialize checksum */
> -	csum = msg->command + args.flags +
> -		args.command_version + args.data_size;
> +	sum = msg->command + args.flags + args.command_version + args.data_size;
>  
>  	/* Copy data and update checksum */
> -	for (i = 0; i < msg->outsize; i++) {
> -		outb(msg->data[i], EC_LPC_ADDR_HOST_PARAM + i);
> -		csum += msg->data[i];
> -	}
> +	sum += cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_PARAM, msg->outsize,
> +				       msg->data);
>  
>  	/* 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);
> +	args.checksum = sum;
> +	cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_ARGS, sizeof(args),
> +				(u8 *)&args);
>  
>  	/* Here we go */
> -	outb(msg->command, EC_LPC_ADDR_HOST_CMD);
> +	sum = msg->command;
> +	cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_CMD, 1, &sum);
>  
>  	if (ec_response_timed_out()) {
>  		dev_warn(ec->dev, "EC responsed timed out\n");
> @@ -165,16 +158,14 @@ static int cros_ec_cmd_xfer_lpc(struct cros_ec_device *ec,
>  	}
>  
>  	/* Check result */
> -	msg->result = inb(EC_LPC_ADDR_HOST_DATA);
> +	msg->result = cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_DATA, 1, &sum);
>  	ret = cros_ec_check_result(ec, msg);
>  	if (ret)
>  		goto done;
>  
>  	/* 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);
> +	cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_ARGS, sizeof(args),
> +			       (u8 *)&args);
>  
>  	if (args.data_size > msg->insize) {
>  		dev_err(ec->dev,
> @@ -185,20 +176,17 @@ static int cros_ec_cmd_xfer_lpc(struct cros_ec_device *ec,
>  	}
>  
>  	/* Start calculating response checksum */
> -	csum = msg->command + args.flags +
> -		args.command_version + args.data_size;
> +	sum = msg->command + args.flags + args.command_version + args.data_size;
>  
>  	/* Read response and update checksum */
> -	for (i = 0; i < args.data_size; i++) {
> -		msg->data[i] = inb(EC_LPC_ADDR_HOST_PARAM + i);
> -		csum += msg->data[i];
> -	}
> +	sum += cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_PARAM, args.data_size,
> +				      msg->data);
>  
>  	/* Verify checksum */
> -	if (args.checksum != (csum & 0xFF)) {
> +	if (args.checksum != sum) {
>  		dev_err(ec->dev,
>  			"bad packet checksum, expected %02x, got %02x\n",
> -			args.checksum, csum & 0xFF);
> +			args.checksum, sum);
>  		ret = -EBADMSG;
>  		goto done;
>  	}
> @@ -222,14 +210,13 @@ static int cros_ec_lpc_readmem(struct cros_ec_device *ec, unsigned int offset,
>  
>  	/* fixed length */
>  	if (bytes) {
> -		for (; cnt < bytes; i++, s++, cnt++)
> -			*s = inb(EC_LPC_ADDR_MEMMAP + i);
> -		return cnt;
> +		cros_ec_lpc_read_bytes(EC_LPC_ADDR_MEMMAP + offset, bytes, s);
> +		return bytes;
>  	}
>  
>  	/* string */
>  	for (; i < EC_MEMMAP_SIZE; i++, s++) {
> -		*s = inb(EC_LPC_ADDR_MEMMAP + i);
> +		cros_ec_lpc_read_bytes(EC_LPC_ADDR_MEMMAP + i, 1, s);
>  		cnt++;
>  		if (!*s)
>  			break;
> @@ -242,6 +229,7 @@ static int cros_ec_lpc_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
>  	struct cros_ec_device *ec_dev;
> +	u8 buf[2];
>  	int ret;
>  
>  	if (!devm_request_region(dev, EC_LPC_ADDR_MEMMAP, EC_MEMMAP_SIZE,
> @@ -250,8 +238,8 @@ static int cros_ec_lpc_probe(struct platform_device *pdev)
>  		return -EBUSY;
>  	}
>  
> -	if ((inb(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID) != 'E') ||
> -	    (inb(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID + 1) != 'C')) {
> +	cros_ec_lpc_read_bytes(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID, 2, buf);
> +	if (buf[0] != 'E' || buf[1] != 'C') {
>  		dev_err(dev, "EC ID not detected\n");
>  		return -ENODEV;
>  	}
> diff --git a/drivers/platform/chrome/cros_ec_lpc_reg.c b/drivers/platform/chrome/cros_ec_lpc_reg.c
> new file mode 100644
> index 0000000..03c9781
> --- /dev/null
> +++ b/drivers/platform/chrome/cros_ec_lpc_reg.c
> @@ -0,0 +1,64 @@
> +/*
> + * cros_ec_lpc_reg - LPC access to the Chrome OS Embedded Controller
> + *
> + * Copyright (C) 2016 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/io.h>
> +#include <linux/mfd/cros_ec.h>
> +#include <linux/mfd/cros_ec_commands.h>
> +
> +static u8 lpc_read_bytes(unsigned int offset, unsigned int length, u8 *dest)
> +{
> +	int i;
> +	int sum = 0;
> +
> +	for (i = 0; i < length; ++i) {
> +		dest[i] = inb(offset + i);
> +		sum += dest[i];
> +	}
> +
> +	/* Return checksum of all bytes read */
> +	return sum;
> +}
> +
> +static u8 lpc_write_bytes(unsigned int offset, unsigned int length, u8 *msg)
> +{
> +	int i;
> +	int sum = 0;
> +
> +	for (i = 0; i < length; ++i) {
> +		outb(msg[i], offset + i);
> +		sum += msg[i];
> +	}
> +
> +	/* Return checksum of all bytes written */
> +	return sum;
> +}
> +
> +u8 cros_ec_lpc_read_bytes(unsigned int offset, unsigned int length, u8 *dest)
> +{
> +	return lpc_read_bytes(offset, length, dest);
> +}
> +
> +u8 cros_ec_lpc_write_bytes(unsigned int offset, unsigned int length, u8 *msg)
> +{
> +	return lpc_write_bytes(offset, length, msg);
> +}
> diff --git a/include/linux/mfd/cros_ec_lpc_reg.h b/include/linux/mfd/cros_ec_lpc_reg.h
> new file mode 100644
> index 0000000..4089bd5
> --- /dev/null
> +++ b/include/linux/mfd/cros_ec_lpc_reg.h
> @@ -0,0 +1,47 @@
> +/*
> + * cros_ec_lpc_reg - LPC access to the Chrome OS Embedded Controller
> + *
> + * Copyright (C) 2016 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.
> + */
> +
> +#ifndef __LINUX_MFD_CROS_EC_REG_H
> +#define __LINUX_MFD_CROS_EC_REG_H
> +
> +/**
> + * cros_ec_lpc_read_bytes - Read bytes from a given LPC-mapped address.
> + * Returns 8-bit checksum of all bytes read.
> + *
> + * @offset: Base read address
> + * @length: Number of bytes to read
> + * @dest: Destination buffer
> + */
> +u8 cros_ec_lpc_read_bytes(unsigned int offset, unsigned int length, u8 *dest);
> +
> +/**
> + * cros_ec_lpc_write_bytes - Write bytes to a given LPC-mapped address.
> + * Returns 8-bit checksum of all bytes written.
> + *
> + * @offset: Base write address
> + * @length: Number of bytes to write
> + * @msg: Write data buffer
> + */
> +u8 cros_ec_lpc_write_bytes(unsigned int offset, unsigned int length, u8 *msg);
> +
> +#endif /* __LINUX_MFD_CROS_EC_REG_H */

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org â Open source software for ARM SoCs
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