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Date: Fri, 25 Sep 2020 12:29:45 +0300
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Jonathan Neuschäfer <j.neuschaefer@....net>
Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Lee Jones <lee.jones@...aro.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 <devicetree@...r.kernel.org>,
linux-pwm@...r.kernel.org,
"open list:REAL TIME CLOCK (RTC) SUBSYSTEM"
<linux-rtc@...r.kernel.org>,
linux-arm Mailing List <linux-arm-kernel@...ts.infradead.org>,
Heiko Stuebner <heiko@...ech.de>,
Josua Mayer <josua.mayer@....eu>,
Andreas Kemnade <andreas@...nade.info>,
Arnd Bergmann <arnd@...db.de>, Daniel Palmer <daniel@...f.com>
Subject: Re: [PATCH v3 3/7] mfd: Add base driver for Netronix embedded controller
On Thu, Sep 24, 2020 at 10:26 PM Jonathan Neuschäfer
<j.neuschaefer@....net> wrote:
>
> The Netronix embedded controller is a microcontroller found in some
> e-book readers designed by the ODM Netronix, Inc. It contains RTC,
> battery monitoring, system power management, and PWM functionality.
>
> This driver implements register access and version detection.
>
> Third-party hardware documentation is available at:
>
> https://github.com/neuschaefer/linux/wiki/Netronix-MSP430-embedded-controller
>
> The EC supports interrupts, but the driver doesn't make use of them so
> far.
...
> +#include <asm/unaligned.h>
This usually goes after linux/*.h
(and actually not visible how it's being used, but see below first)
> +#include <linux/delay.h>
> +#include <linux/errno.h>
> +#include <linux/i2c.h>
> +#include <linux/mfd/core.h>
> +#include <linux/mfd/ntxec.h>
> +#include <linux/module.h>
> +#include <linux/pm.h>
> +#include <linux/reboot.h>
> +#include <linux/regmap.h>
> +#include <linux/types.h>
...
> +static void ntxec_poweroff(void)
> +{
> + int res;
> + u8 buf[] = {
> + NTXEC_REG_POWEROFF,
> + (NTXEC_POWEROFF_VALUE >> 8) & 0xff,
> + NTXEC_POWEROFF_VALUE & 0xff,
'& 0xff' parts are redundant. *u8 implies that. Fix in all cases.
Also I would rather see something like
buf[0] = _POWEROFF;
put_unaligned_be16(_VALUE, &buf[1]);
to explicitly show the endianess of the register values.
> + };
> + struct i2c_msg msgs[] = {
> + {
> + .addr = poweroff_restart_client->addr,
> + .flags = 0,
> + .len = sizeof(buf),
> + .buf = buf
It's slightly better to keep trailing commas in cases like this.
> + }
> + };
> +
> + res = i2c_transfer(poweroff_restart_client->adapter, msgs, ARRAY_SIZE(msgs));
> + if (res < 0)
> + dev_alert(&poweroff_restart_client->dev,
> + "Failed to power off (err = %d)\n", res);
alert? This needs to be explained.
> + /*
> + * The time from the register write until the host CPU is powered off
> + * has been observed to be about 2.5 to 3 seconds. Sleep long enough to
> + * safely avoid returning from the poweroff handler.
> + */
> + msleep(5000);
> +}
> +
> +static int ntxec_restart(struct notifier_block *nb,
> + unsigned long action, void *data)
> +{
> + int res;
> + /*
> + * NOTE: The lower half of the reset value is not sent, because sending
> + * it causes an error
Why? Any root cause? Perhaps you need to send 0xffff ?
> + */
> + u8 buf[] = {
> + NTXEC_REG_RESET,
> + (NTXEC_RESET_VALUE >> 8) & 0xff,
Here you may still use put_unaligned_be16() but move the comment to be
before len hardcoded to sizeof(buf) - 1.
> + };
> + struct i2c_msg msgs[] = {
> + {
> + .addr = poweroff_restart_client->addr,
> + .flags = 0,
> + .len = sizeof(buf),
> + .buf = buf
> + }
> + };
> +
> + res = i2c_transfer(poweroff_restart_client->adapter, msgs, ARRAY_SIZE(msgs));
> + if (res < 0)
> + dev_alert(&poweroff_restart_client->dev,
> + "Failed to restart (err = %d)\n", res);
> +
> + return NOTIFY_DONE;
> +}
...
> +static int ntxec_probe(struct i2c_client *client)
> +{
> + struct ntxec *ec;
> + unsigned int version;
> + int res;
> +
> + ec = devm_kmalloc(&client->dev, sizeof(*ec), GFP_KERNEL);
> + if (!ec)
> + return -ENOMEM;
> +
> + ec->dev = &client->dev;
> +
> + ec->regmap = devm_regmap_init_i2c(client, ®map_config);
> + if (IS_ERR(ec->regmap)) {
> + dev_err(ec->dev, "Failed to set up regmap for device\n");
> + return res;
> + }
> +
> + /* Determine the firmware version */
> + res = regmap_read(ec->regmap, NTXEC_REG_VERSION, &version);
> + if (res < 0) {
> + dev_err(ec->dev, "Failed to read firmware version number\n");
> + return res;
> + }
> + dev_info(ec->dev,
> + "Netronix embedded controller version %04x detected.\n",
> + version);
This info level may confuse users if followed by an error path.
> + /* Bail out if we encounter an unknown firmware version */
> + switch (version) {
> + case 0xd726: /* found in Kobo Aura */
> + break;
> + default:
> + return -ENODEV;
> + }
> +
> + 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 = regmap_write(ec->regmap, NTXEC_REG_POWERKEEP,
> + NTXEC_POWERKEEP_VALUE);
> + if (res < 0)
> + return res;
> + WARN_ON(poweroff_restart_client);
WARN_ON? All these alerts, WARNs, BUGs must be explained. Screaming to
the user is not good if it wasn't justified.
> + poweroff_restart_client = client;
> + if (pm_power_off)
> + dev_err(ec->dev, "pm_power_off already assigned\n");
> + else
> + pm_power_off = ntxec_poweroff;
> +
> + res = register_restart_handler(&ntxec_restart_handler);
> + if (res)
> + dev_err(ec->dev,
> + "Failed to register restart handler: %d\n", res);
> + }
> +
> + i2c_set_clientdata(client, ec);
> +
> + res = devm_mfd_add_devices(ec->dev, PLATFORM_DEVID_NONE, ntxec_subdevices,
> + ARRAY_SIZE(ntxec_subdevices), NULL, 0, NULL);
> + if (res)
> + dev_warn(ec->dev, "Failed to add subdevices: %d\n", res);
'warn' is inconsistent with 'return err'. Either do not return an
error, or mark a message as an error one.
And above with the restart handler has the same issue.
> + return res;
> +}
> +
> +static int ntxec_remove(struct i2c_client *client)
> +{
> + if (client == poweroff_restart_client) {
When it's not the case?
> + poweroff_restart_client = NULL;
> + pm_power_off = NULL;
> + unregister_restart_handler(&ntxec_restart_handler);
> + }
> +
> + return 0;
> +}
...
> +#include <linux/types.h>
> +
Missed
struct device;
struct regmap;
here.
> +struct ntxec {
> + struct device *dev;
> + struct regmap *regmap;
> +};
> +/*
> + * Some registers, such as the battery status register (0x41), are in
> + * big-endian, but others only have eight significant bits, which are in the
> + * first byte transmitted over I2C (the MSB of the big-endian value).
> + * This convenience function converts an 8-bit value to 16-bit for use in the
> + * second kind of register.
> + */
> +static inline u16 ntxec_reg8(u8 value)
> +{
> + return value << 8;
> +}
I'm wondering why __be16 is not used as returned type.
--
With Best Regards,
Andy Shevchenko
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