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Message-ID: <20200622105544.GU954398@dell>
Date: Mon, 22 Jun 2020 11:55:44 +0100
From: Lee Jones <lee.jones@...aro.org>
To: Jonathan Neuschäfer <j.neuschaefer@....net>
Cc: linux-kernel@...r.kernel.org, Rob Herring <robh+dt@...nel.org>,
Thierry Reding <thierry.reding@...il.com>,
Uwe Kleine-König
<u.kleine-koenig@...gutronix.de>,
Alessandro Zummo <a.zummo@...ertech.it>,
Alexandre Belloni <alexandre.belloni@...tlin.com>,
Shawn Guo <shawnguo@...nel.org>,
Sascha Hauer <s.hauer@...gutronix.de>,
Pengutronix Kernel Team <kernel@...gutronix.de>,
Fabio Estevam <festevam@...il.com>,
NXP Linux Team <linux-imx@....com>,
Sam Ravnborg <sam@...nborg.org>,
Linus Walleij <linus.walleij@...aro.org>,
Heiko Stuebner <heiko.stuebner@...obroma-systems.com>,
Stephan Gerhold <stephan@...hold.net>,
Lubomir Rintel <lkundrak@...sk>,
Mark Brown <broonie@...nel.org>, allen <allen.chen@....com.tw>,
Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
"David S. Miller" <davem@...emloft.net>,
devicetree@...r.kernel.org, linux-pwm@...r.kernel.org,
linux-rtc@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
Heiko Stuebner <heiko@...ech.de>,
Josua Mayer <josua.mayer@....eu>,
Andreas Kemnade <andreas@...nade.info>
Subject: Re: [RFC PATCH 04/10] mfd: Add base driver for Netronix embedded
controller
On Sun, 21 Jun 2020, Jonathan Neuschäfer wrote:
Description of the device here please.
> Third-party hardware documentation is available at
'\n'
> https://github.com/neuschaefer/linux/wiki/Netronix-MSP430-embedded-controller
Indent this with a couple of spaces.
> The EC supports interrupts, but the driver doesn't make use of them so
> far.
>
> Known problems:
> - The reboot handler is installed in such a way that it directly calls
> into the i2c subsystem to send the reboot command to the EC. This
> means that the reboot handler may sleep, which is not allowed.
>
> Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@....net>
> ---
> drivers/mfd/Kconfig | 7 ++
> drivers/mfd/Makefile | 1 +
> drivers/mfd/ntxec.c | 188 ++++++++++++++++++++++++++++++++++++++
> include/linux/mfd/ntxec.h | 30 ++++++
> 4 files changed, 226 insertions(+)
> create mode 100644 drivers/mfd/ntxec.c
> create mode 100644 include/linux/mfd/ntxec.h
>
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index a37d7d1713820..78410b928648e 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -978,6 +978,13 @@ config MFD_VIPERBOARD
> You need to select the mfd cell drivers separately.
> The drivers do not support all features the board exposes.
>
> +config MFD_NTXEC
> + bool "Netronix Embedded Controller"
> + depends on I2C && OF
> + help
> + Say yes here if you want to support the embedded controller of
> + certain e-book readers designed by the ODM Netronix.
s/of certain/found in certain/.
> config MFD_RETU
> tristate "Nokia Retu and Tahvo multi-function device"
> select MFD_CORE
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index 9367a92f795a6..19d9391ed6f32 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -218,6 +218,7 @@ obj-$(CONFIG_MFD_INTEL_MSIC) += intel_msic.o
> obj-$(CONFIG_MFD_INTEL_PMC_BXT) += intel_pmc_bxt.o
> obj-$(CONFIG_MFD_PALMAS) += palmas.o
> obj-$(CONFIG_MFD_VIPERBOARD) += viperboard.o
> +obj-$(CONFIG_MFD_NTXEC) += ntxec.o
> obj-$(CONFIG_MFD_RC5T583) += rc5t583.o rc5t583-irq.o
> obj-$(CONFIG_MFD_RK808) += rk808.o
> obj-$(CONFIG_MFD_RN5T618) += rn5t618.o
> diff --git a/drivers/mfd/ntxec.c b/drivers/mfd/ntxec.c
> new file mode 100644
> index 0000000000000..82adea34ea746
> --- /dev/null
> +++ b/drivers/mfd/ntxec.c
> @@ -0,0 +1,188 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +// Copyright 2020 Jonathan Neuschäfer
> +//
> +// MFD driver for the usually MSP430-based embedded controller used in certain
> +// Netronix ebook reader board designs
Only the SPDX line should contain C++ style comments.
Description at the top, copyright after.
An "MFD driver" isn't really a thing. Please describe the device.
> +#include <asm/unaligned.h>
> +#include <linux/delay.h>
> +#include <linux/errno.h>
> +#include <linux/i2c.h>
> +#include <linux/mfd/ntxec.h>
> +#include <linux/of_platform.h>
> +#include <linux/pm.h>
> +#include <linux/reboot.h>
> +#include <linux/types.h>
> +
> +
No need for double line spacing.
> +#define NTXEC_VERSION 0x00
> +#define NTXEC_POWEROFF 0x50
> +#define NTXEC_POWERKEEP 0x70
> +#define NTXEC_RESET 0x90
Are these registers? Might be worth pre/post-fixing with _REG.
> +/* Register access */
> +
> +int ntxec_read16(struct ntxec *ec, u8 addr)
> +{
> + u8 request[1] = { addr };
> + u8 response[2];
> + int res;
> +
> + struct i2c_msg msgs[] = {
> + {
> + .addr = ec->client->addr,
> + .flags = ec->client->flags,
> + .len = sizeof(request),
> + .buf = request
> + }, {
> + .addr = ec->client->addr,
> + .flags = ec->client->flags | I2C_M_RD,
> + .len = sizeof(response),
> + .buf = response
> + }
> + };
> +
> + res = i2c_transfer(ec->client->adapter, msgs, ARRAY_SIZE(msgs));
> + if (res < 0)
> + return res;
> + if (res != ARRAY_SIZE(msgs))
> + return -EIO;
> +
> + return get_unaligned_be16(response);
> +}
> +EXPORT_SYMBOL(ntxec_read16);
> +
> +int ntxec_write16(struct ntxec *ec, u8 addr, u16 value)
> +{
> + u8 request[3] = { addr, };
> + int res;
> +
> + put_unaligned_be16(value, request + 1);
> +
> + res = i2c_transfer_buffer_flags(ec->client, request, sizeof(request),
> + ec->client->flags);
> + if (res < 0)
> + return res;
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(ntxec_write16);
> +
> +int ntxec_read8(struct ntxec *ec, u8 addr)
> +{
> + int res = ntxec_read16(ec, addr);
> +
> + if (res < 0)
> + return res;
> +
> + return (res >> 8) & 0xff;
> +}
> +EXPORT_SYMBOL(ntxec_read8);
> +
> +int ntxec_write8(struct ntxec *ec, u8 addr, u8 value)
> +{
> + return ntxec_write16(ec, addr, value << 8);
> +}
> +EXPORT_SYMBOL(ntxec_write8);
Why are you hand-rolling your own accessors?
> +
> +
> +/* Reboot/poweroff handling */
These comments seem to be stating the obvious.
Please remove them.
> +static struct ntxec *poweroff_restart_instance;
> +
> +static void ntxec_poweroff(void)
> +{
> + ntxec_write8(poweroff_restart_instance, NTXEC_POWEROFF, 0x01);
All magic numbers should be defined?
> + msleep(5000);
Why 5000?
> +}
> +
> +static int ntxec_restart(struct notifier_block *nb,
> + unsigned long action, void *data)
> +{
> + /* FIXME: The I2C driver sleeps, but restart handlers may not sleep */
Then this is not allowed.
You need to fix this *before* submitting upstream.
> + ntxec_write8(poweroff_restart_instance, NTXEC_RESET, 0xff);
> + /* TODO: delay? */
TODO *before* submitting upstream. This is not a development branch.
> + return NOTIFY_DONE;
> +}
> +
> +static struct notifier_block ntxec_restart_handler = {
> + .notifier_call = ntxec_restart,
> + .priority = 128
> +};
> +
> +
> +/* Driver setup */
> +
> +static int ntxec_probe(struct i2c_client *client,
> + const struct i2c_device_id *ids)
> +{
> + struct ntxec *ec;
> + int res;
What does 'res' mean?
> + ec = devm_kmalloc(&client->dev, sizeof(*ec), GFP_KERNEL);
> + if (!ec)
> + return -ENOMEM;
> +
> + ec->dev = &client->dev;
> + ec->client = client;
You don't need both (if any).
> + /* Determine the firmware version */
> + res = ntxec_read16(ec, NTXEC_VERSION);
> + if (res < 0) {
> + dev_dbg(ec->dev, "Failed to read firmware version number\n");
Why dbg?
> + return res;
> + }
> + ec->version = res;
> +
> + dev_info(ec->dev,
> + "Netronix embedded controller version %04x detected.\n",
> + ec->version);
> +
> + /* For now, we don't support the new register layout. */
> + if (ntxec_has_new_layout(ec))
> + return -EOPNOTSUPP;
What is the new layout?
Why don't you support it?
> + if (of_device_is_system_power_controller(ec->dev->of_node)) {
> + /*
> + * Set the 'powerkeep' bit. This is necessary on some boards
> + * in order to keep the system running.
> + */
> + res = ntxec_write8(ec, NTXEC_POWERKEEP, 0x08);
> + if (res < 0)
> + return res;
> +
> + /* Install poweroff handler */
> + WARN_ON(poweroff_restart_instance);
Why WARN?
> + poweroff_restart_instance = ec;
> + if (pm_power_off != NULL)
if (pm_power_off)
> + /* TODO: Refactor among all poweroff drivers */
Nope.
> + dev_err(ec->dev, "pm_power_off already assigned\n");
Error, but execution carries on anyway?
> + else
> + pm_power_off = ntxec_poweroff;
> +
> + /* Install board reset handler */
> + res = register_restart_handler(&ntxec_restart_handler);
> + if (res < 0)
Is >0 valid?
> + dev_err(ec->dev,
> + "Failed to register restart handler: %d\n", res);
> + }
> +
> + i2c_set_clientdata(client, ec);
Where do you use this?
> + return devm_of_platform_populate(ec->dev);
> +}
> +
> +static const struct of_device_id of_ntxec_match_table[] = {
> + { .compatible = "netronix,ntxec", },
> + {}
> +};
Use .probe_new() and drop this.
> +static struct i2c_driver ntxec_driver = {
> + .driver = {
> + .name = "ntxec",
> + .of_match_table = of_ntxec_match_table,
> + },
> + .probe = ntxec_probe,
Nothing to .remove()?
> +};
> +builtin_i2c_driver(ntxec_driver);
Only built-in?
> diff --git a/include/linux/mfd/ntxec.h b/include/linux/mfd/ntxec.h
> new file mode 100644
> index 0000000000000..9f9d6f2141751
> --- /dev/null
> +++ b/include/linux/mfd/ntxec.h
> @@ -0,0 +1,30 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright 2020 Jonathan Neuschäfer
> + *
> + * MFD access functions for the Netronix embedded controller.
No such thing as an MFD.
"Embedded Controller"
> + */
> +
> +#ifndef NTXEC_H
> +#define NTXEC_H
> +
> +#include <linux/types.h>
> +
> +struct ntxec {
> + struct device *dev;
> + struct i2c_client *client;
> + u16 version;
> + /* TODO: Add a mutex to protect actions consisting of multiple accesses? */
No TODOs. Please fix before upstreaming.
> +};
> +
> +static inline bool ntxec_has_new_layout(struct ntxec *ec)
> +{
> + return ec->version == 0xe916;
Why don't you just check for the devices you *do* support?
> +}
> +
> +int ntxec_read16(struct ntxec *ec, u8 addr);
> +int ntxec_write16(struct ntxec *ec, u8 addr, u16 value);
> +int ntxec_read8(struct ntxec *ec, u8 addr);
> +int ntxec_write8(struct ntxec *ec, u8 addr, u8 value);
> +
> +#endif
#endif /* NTXEC_H */
--
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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