Date:   Wed, 30 Nov 2016 16:48:28 +0100
From:   Enric Balletbo Serra <eballetbo@...il.com>
To:     Thierry Escande <thierry.escande@...labora.com>
Cc:     Benson Leung <bleung@...omium.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RESEND 2/2] platform/chrome: cros_ec_lpc: Add support for
 mec1322 EC

Hi Thierry,

I reviewed your patches and looks good to me, I only found a few style
things that is up to maintainer decide if are needed or not, most of
them are feedback I received on other subsystems. Ah, and I've a
question about runtime detection of the EC (see below), but guess the
answer is no.

Reviewed-by: Enric Balletbo i Serra <enric.balletbo@...labora.com>

2016-11-08 13:27 GMT+01:00 Thierry Escande <thierry.escande@...labora.com>:
> From: Shawn Nematbakhsh <shawnn@...omium.org>
>
> This adds support for the ChromeOS LPC Microchip Embedded Controller
> (mec1322) variant.
>
> mec1322 accesses I/O region [800h, 9ffh] through embedded memory
> interface (EMI) rather than LPC.
>
> Signed-off-by: Shawn Nematbakhsh <shawnn@...omium.org>
> Signed-off-by: Gwendal Grignou <gwendal@...omium.org>
> Signed-off-by: Guenter Roeck <groeck@...omium.org>
> Signed-off-by: Thierry Escande <thierry.escande@...labora.com>
> ---
>  drivers/platform/chrome/Kconfig           |   9 ++
>  drivers/platform/chrome/Makefile          |   1 +
>  drivers/platform/chrome/cros_ec_lpc.c     |   5 ++
>  drivers/platform/chrome/cros_ec_lpc_mec.c | 144 ++++++++++++++++++++++++++++++
>  drivers/platform/chrome/cros_ec_lpc_reg.c |  69 ++++++++++++++
>  include/linux/mfd/cros_ec_lpc_mec.h       |  93 +++++++++++++++++++
>  include/linux/mfd/cros_ec_lpc_reg.h       |  14 +++
>  7 files changed, 335 insertions(+)
>  create mode 100644 drivers/platform/chrome/cros_ec_lpc_mec.c
>  create mode 100644 include/linux/mfd/cros_ec_lpc_mec.h
>
> diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig
> index 76bdae1..55149f2 100644
> --- a/drivers/platform/chrome/Kconfig
> +++ b/drivers/platform/chrome/Kconfig
> @@ -59,6 +59,15 @@ config CROS_EC_LPC
>            To compile this driver as a module, choose M here: the
>            module will be called cros_ec_lpc.
>
> +config CROS_EC_LPC_MEC
> +       bool "ChromeOS Embedded Controller LPC Microchip EC (MEC) variant"
> +       depends on CROS_EC_LPC
> +       default n
> +       help
> +         If you say Y here, a variant LPC protocol for the Microchip EC
> +         will be used. Note that this variant is not backward compatible
> +         with non-Microchip ECs.
> +

As reported by checkpatch, write a paragraph that describes the config
symbol fully. Maybe adding something like this

          If you have a ChromeOS Embedded Controller Microchip EC variant
          choose Y here.

According to the help if you have a non-Microchip EC you should leave
this as N. Would be possible some kind of runtime detection of the EC
? Just thinking in out loud.

>  config CROS_EC_PROTO
>          bool
>          help
> diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
> index 127fbe8..b8f7a3b 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
>  obj-$(CONFIG_CROS_EC_CHARDEV)          += cros_ec_devs.o
>  cros_ec_lpcs-objs                      := cros_ec_lpc.o cros_ec_lpc_reg.o
> +cros_ec_lpcs-$(CONFIG_CROS_EC_LPC_MEC) += cros_ec_lpc_mec.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 617074e..264234b 100644
> --- a/drivers/platform/chrome/cros_ec_lpc.c
> +++ b/drivers/platform/chrome/cros_ec_lpc.c
> @@ -349,10 +349,13 @@ static int __init cros_ec_lpc_init(void)
>                 return -ENODEV;
>         }
>
> +       cros_ec_lpc_reg_init();
> +
>         /* Register the driver */
>         ret = platform_driver_register(&cros_ec_lpc_driver);
>         if (ret) {
>                 pr_err(DRV_NAME ": can't register driver: %d\n", ret);
> +               cros_ec_lpc_reg_destroy();
>                 return ret;
>         }
>
> @@ -361,6 +364,7 @@ static int __init cros_ec_lpc_init(void)
>         if (ret) {
>                 pr_err(DRV_NAME ": can't register device: %d\n", ret);
>                 platform_driver_unregister(&cros_ec_lpc_driver);
> +               cros_ec_lpc_reg_destroy();
>                 return ret;
>         }
>
> @@ -371,6 +375,7 @@ static void __exit cros_ec_lpc_exit(void)
>  {
>         platform_device_unregister(&cros_ec_lpc_device);
>         platform_driver_unregister(&cros_ec_lpc_driver);
> +       cros_ec_lpc_reg_destroy();
>  }
>
>  module_init(cros_ec_lpc_init);
> diff --git a/drivers/platform/chrome/cros_ec_lpc_mec.c b/drivers/platform/chrome/cros_ec_lpc_mec.c
> new file mode 100644
> index 0000000..09e2e21
> --- /dev/null
> +++ b/drivers/platform/chrome/cros_ec_lpc_mec.c
> @@ -0,0 +1,144 @@
> +/*
> + * cros_ec_lpc_mec - LPC variant I/O for Microchip EC
> + *
> + * Copyright (C) 2015 Google, Inc
> + *

Update the copyright to 2016

> + * 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/io.h>
> +#include <linux/mfd/cros_ec_commands.h>
> +#include <linux/mfd/cros_ec_lpc_mec.h>
> +#include <linux/mutex.h>
> +#include <linux/types.h>
> +
> +/*
> + * This mutex must be held while accessing the EMI unit. We can't rely on the
> + * EC mutex because memmap data may be accessed without it being held.
> + */
> +static struct mutex io_mutex;
> +
> +/*
> + * cros_ec_lpc_mec_emi_write_address
> + *
> + * Initialize EMI read / write at a given address.
> + *
> + * @addr:        Starting read / write address
> + * @access_type: Type of access, typically 32-bit auto-increment
> + */
> +static void cros_ec_lpc_mec_emi_write_address(
> +       uint16_t addr,

It is preferred use type u16 over uint16_t

> +       enum cros_ec_lpc_mec_emi_access_mode access_type)
> +{
> +       /* Address relative to start of EMI range */
> +       addr -= MEC_EMI_RANGE_START;
> +       outb((addr & 0xfc) | access_type, MEC_EMI_EC_ADDRESS_B0);
> +       outb((addr >> 8) & 0x7f, MEC_EMI_EC_ADDRESS_B1);
> +}
> +
> +/*
> + * cros_ec_lpc_io_bytes_mec - Read / write bytes to MEC EMI port
> + *
> + * @io_type: MEC_IO_READ or MEC_IO_WRITE, depending on request
> + * @offset:  Base read / write address
> + * @length:  Number of bytes to read / write
> + * @buf:     Destination / source buffer
> + *
> + * @return 8-bit checksum of all bytes read / written
> + */
> +u8 cros_ec_lpc_io_bytes_mec(
> +       enum cros_ec_lpc_mec_io_type io_type,
> +       unsigned int offset,
> +       unsigned int length,
> +       u8 *buf)

nit: When possible alignment should match open parenthesis. I'd define
the function as:

u8 cros_ec_lpc_io_bytes_mec(enum cros_ec_lpc_mec_io_type io_type,
                                             unsigned int offset,
unsigned int length, u8 *buf)

> +{
> +       int i = 0;
> +       int io_addr;
> +       u8 sum = 0;
> +       enum cros_ec_lpc_mec_emi_access_mode access, new_access;
> +
> +       /*
> +        * Long access cannot be used on misaligned data since reading B0 loads
> +        * the data register and writing B3 flushes.
> +        */
> +       if ((offset & 0x3) || length < 4)
> +               access = ACCESS_TYPE_BYTE;
> +       else
> +               access = ACCESS_TYPE_LONG_AUTO_INCREMENT;
> +
> +       mutex_lock(&io_mutex);
> +
> +       /* Initialize I/O at desired address */
> +       cros_ec_lpc_mec_emi_write_address(
> +               offset,
> +               access);
> +

This fits in one line.

> +       /* Skip bytes in case of misaligned offset */
> +       io_addr = MEC_EMI_EC_DATA_B0 + (offset & 0x3);
> +       while (i < length) {
> +               while (io_addr <= MEC_EMI_EC_DATA_B3) {
> +                       if (io_type == MEC_IO_READ)
> +                               buf[i] = inb(io_addr++);
> +                       else
> +                               outb(buf[i], io_addr++);
> +
> +                       sum += buf[i++];
> +                       offset++;
> +
> +                       /* Extra bounds check in case of misaligned length */
> +                       if (i == length)
> +                               goto done;
> +               }
> +
> +               /*
> +                * Use long auto-increment access except for misaligned write,
> +                * since writing B3 triggers the flush.
> +                */
> +               if (length - i < 4 && io_type == MEC_IO_WRITE)
> +                       new_access = ACCESS_TYPE_BYTE;
> +               else
> +                       new_access = ACCESS_TYPE_LONG_AUTO_INCREMENT;
> +               if (new_access != access ||
> +                   access != ACCESS_TYPE_LONG_AUTO_INCREMENT) {
> +                       access = new_access;
> +                       cros_ec_lpc_mec_emi_write_address(
> +                               offset,
> +                               access);

This also fits in one line.

> +               }
> +
> +               /* Access [B0, B3] on each loop pass */
> +               io_addr = MEC_EMI_EC_DATA_B0;
> +       }
> +done:
> +       mutex_unlock(&io_mutex);

Add an empty line here

> +       return sum;
> +}
> +EXPORT_SYMBOL(cros_ec_lpc_io_bytes_mec);
> +
> +void cros_ec_lpc_mec_init(void)
> +{
> +       mutex_init(&io_mutex);
> +}
> +EXPORT_SYMBOL(cros_ec_lpc_mec_init);
> +
> +void cros_ec_lpc_mec_destroy(void)
> +{
> +       mutex_destroy(&io_mutex);
> +}
> +EXPORT_SYMBOL(cros_ec_lpc_mec_destroy);
> diff --git a/drivers/platform/chrome/cros_ec_lpc_reg.c b/drivers/platform/chrome/cros_ec_lpc_reg.c
> index 672d08c..afb29c4 100644
> --- a/drivers/platform/chrome/cros_ec_lpc_reg.c
> +++ b/drivers/platform/chrome/cros_ec_lpc_reg.c
> @@ -24,6 +24,7 @@
>  #include <linux/io.h>
>  #include <linux/mfd/cros_ec.h>
>  #include <linux/mfd/cros_ec_commands.h>
> +#include <linux/mfd/cros_ec_lpc_mec.h>
>
>  static u8 lpc_read_bytes(unsigned int offset, unsigned int length, u8 *dest)
>  {
> @@ -53,12 +54,80 @@ static u8 lpc_write_bytes(unsigned int offset, unsigned int length, u8 *msg)
>         return sum;
>  }
>
> +#ifdef CONFIG_CROS_EC_LPC_MEC
> +
>  u8 cros_ec_lpc_read_bytes(unsigned int offset, unsigned int length, u8 *dest)
>  {
> +       if (length == 0)
> +               return 0;
> +
> +       /* Access desired range through EMI interface */
> +       if (offset >= MEC_EMI_RANGE_START && offset <= MEC_EMI_RANGE_END) {
> +               /* Ensure we don't straddle EMI region */
> +               if (WARN_ON(offset + length - 1 > MEC_EMI_RANGE_END))
> +                       return 0;
> +
> +               return cros_ec_lpc_io_bytes_mec(
> +                       MEC_IO_READ, offset, length, dest);
> +       }
> +
> +       if (WARN_ON(offset + length > MEC_EMI_RANGE_START &&
> +                   offset < MEC_EMI_RANGE_START))
> +               return 0;
> +
>         return lpc_read_bytes(offset, length, dest);
>  }
>
>  u8 cros_ec_lpc_write_bytes(unsigned int offset, unsigned int length, u8 *msg)
>  {
> +       if (length == 0)
> +               return 0;
> +
> +       /* Access desired range through EMI interface */
> +       if (offset >= MEC_EMI_RANGE_START && offset <= MEC_EMI_RANGE_END) {
> +               /* Ensure we don't straddle EMI region */
> +               if (WARN_ON(offset + length - 1 > MEC_EMI_RANGE_END))
> +                       return 0;
> +
> +               return cros_ec_lpc_io_bytes_mec(
> +                       MEC_IO_WRITE, offset, length, msg);
> +       }
> +
> +       if (WARN_ON(offset + length > MEC_EMI_RANGE_START &&
> +                   offset < MEC_EMI_RANGE_START))
> +               return 0;
> +
>         return lpc_write_bytes(offset, length, msg);
>  }
> +
> +void cros_ec_lpc_reg_init(void)
> +{
> +       cros_ec_lpc_mec_init();
> +}
> +
> +void cros_ec_lpc_reg_destroy(void)
> +{
> +       cros_ec_lpc_mec_destroy();
> +}
> +
> +#else /* CONFIG_CROS_EC_LPC_MEC */
> +
> +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);
> +}
> +
> +void cros_ec_lpc_reg_init(void)
> +{
> +}
> +
> +void cros_ec_lpc_reg_destroy(void)
> +{
> +}
> +
> +#endif /* CONFIG_CROS_EC_LPC_MEC */
> diff --git a/include/linux/mfd/cros_ec_lpc_mec.h b/include/linux/mfd/cros_ec_lpc_mec.h
> new file mode 100644
> index 0000000..69da593
> --- /dev/null
> +++ b/include/linux/mfd/cros_ec_lpc_mec.h
> @@ -0,0 +1,93 @@
> +/*
> + * cros_ec_lpc_mec - LPC variant I/O for Microchip EC
> + *
> + * Copyright (C) 2015 Google, Inc
> + *

Update the copyright.

> + * 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_MEC_H
> +#define __LINUX_MFD_CROS_EC_MEC_H
> +
> +#include <linux/mfd/cros_ec_commands.h>
> +
> +enum cros_ec_lpc_mec_emi_access_mode {
> +       /* 8-bit access */
> +       ACCESS_TYPE_BYTE = 0x0,
> +       /* 16-bit access */
> +       ACCESS_TYPE_WORD = 0x1,
> +       /* 32-bit access */
> +       ACCESS_TYPE_LONG = 0x2,
> +       /*
> +        * 32-bit access, read or write of MEC_EMI_EC_DATA_B3 causes the
> +        * EC data register to be incremented.
> +        */
> +       ACCESS_TYPE_LONG_AUTO_INCREMENT = 0x3,
> +};
> +
> +enum cros_ec_lpc_mec_io_type {
> +       MEC_IO_READ,
> +       MEC_IO_WRITE,
> +};
> +
> +/* Access IO ranges 0x800 thru 0x9ff using EMI interface instead of LPC */
> +#define MEC_EMI_RANGE_START EC_HOST_CMD_REGION0
> +#define MEC_EMI_RANGE_END   (EC_LPC_ADDR_MEMMAP + EC_MEMMAP_SIZE)
> +
> +/* EMI registers are relative to base */
> +#define MEC_EMI_BASE 0x800
> +#define MEC_EMI_HOST_TO_EC (MEC_EMI_BASE + 0)
> +#define MEC_EMI_EC_TO_HOST (MEC_EMI_BASE + 1)
> +#define MEC_EMI_EC_ADDRESS_B0 (MEC_EMI_BASE + 2)
> +#define MEC_EMI_EC_ADDRESS_B1 (MEC_EMI_BASE + 3)
> +#define MEC_EMI_EC_DATA_B0 (MEC_EMI_BASE + 4)
> +#define MEC_EMI_EC_DATA_B1 (MEC_EMI_BASE + 5)
> +#define MEC_EMI_EC_DATA_B2 (MEC_EMI_BASE + 6)
> +#define MEC_EMI_EC_DATA_B3 (MEC_EMI_BASE + 7)
> +
> +/*
> + * cros_ec_lpc_mec_init
> + *
> + * Initialize MEC I/O.
> + */
> +void cros_ec_lpc_mec_init(void);
> +
> +/*
> + * cros_ec_lpc_mec_destroy
> + *
> + * Cleanup MEC I/O.
> + */
> +void cros_ec_lpc_mec_destroy(void);
> +
> +/**
> + * cros_ec_lpc_io_bytes_mec - Read / write bytes to MEC EMI port
> + *
> + * @io_type: MEC_IO_READ or MEC_IO_WRITE, depending on request
> + * @offset:  Base read / write address
> + * @length:  Number of bytes to read / write
> + * @buf:     Destination / source buffer
> + *
> + * @return 8-bit checksum of all bytes read / written
> + */
> +u8 cros_ec_lpc_io_bytes_mec(
> +       enum cros_ec_lpc_mec_io_type io_type,
> +       unsigned int offset,
> +       unsigned int length,
> +       u8 *buf);
> +
> +#endif /* __LINUX_MFD_CROS_EC_MEC_H */
> diff --git a/include/linux/mfd/cros_ec_lpc_reg.h b/include/linux/mfd/cros_ec_lpc_reg.h
> index f3668ab..daede3a 100644
> --- a/include/linux/mfd/cros_ec_lpc_reg.h
> +++ b/include/linux/mfd/cros_ec_lpc_reg.h
> @@ -44,4 +44,18 @@ u8 cros_ec_lpc_read_bytes(unsigned int offset, unsigned int length, u8 *dest);
>   */
>  u8 cros_ec_lpc_write_bytes(unsigned int offset, unsigned int length, u8 *msg);
>
> +/**
> + * cros_ec_lpc_reg_init
> + *
> + * Initialize register I/O.
> + */
> +void cros_ec_lpc_reg_init(void);
> +
> +/**
> + * cros_ec_lpc_reg_destroy
> + *
> + * Cleanup reg I/O.
> + */
> +void cros_ec_lpc_reg_destroy(void);
> +
>  #endif /* __LINUX_MFD_CROS_EC_REG_H */
> --
> 2.7.4
>

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