Re: [PATCH v4 2/6] platform: arm64: add Lenovo Yoga C630 WOS EC driver

[Dmitry Baryshkov]

On Wed, May 29, 2024 at 12:51:04AM +0100, Bryan O'Donoghue wrote:
> On 28/05/2024 21:44, Dmitry Baryshkov wrote:
> > Lenovo Yoga C630 WOS is a laptop using Snapdragon 850 SoC. Like many
> > laptops it uses embedded controller (EC) to perform various platform
> 
> an embedded controller
> 
> > operations, including, but not limited, to Type-C port control or power
> > supply handlng.
> > 
> > Add the driver for the EC, that creates devices for UCSI and power
> > supply devices.
> > 
> > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> > ---
> >   drivers/platform/arm64/Kconfig                 |  14 ++
> >   drivers/platform/arm64/Makefile                |   1 +
> >   drivers/platform/arm64/lenovo-yoga-c630.c      | 279 +++++++++++++++++++++++++
> >   include/linux/platform_data/lenovo-yoga-c630.h |  42 ++++
> >   4 files changed, 336 insertions(+)
> > 
> > diff --git a/drivers/platform/arm64/Kconfig b/drivers/platform/arm64/Kconfig
> > index 8fdca0f8e909..8c103b3150d1 100644
> > --- a/drivers/platform/arm64/Kconfig
> > +++ b/drivers/platform/arm64/Kconfig
> > @@ -32,4 +32,18 @@ config EC_ACER_ASPIRE1
> >   	  laptop where this information is not properly exposed via the
> >   	  standard ACPI devices.
> > +config EC_LENOVO_YOGA_C630
> > +	tristate "Lenovo Yoga C630 Embedded Controller driver"
> > +	depends on I2C
> > +	help
> > +	  Driver for the Embedded Controller in the Qualcomm Snapdragon-based
> > +	  Lenovo Yoga C630, which provides battery and power adapter
> > +	  information.
> > +
> > +	  This driver provides battery and AC status support for the mentioned
> > +	  laptop where this information is not properly exposed via the
> > +	  standard ACPI devices.
> > +
> > +	  Say M or Y here to include this support.
> > +
> >   endif # ARM64_PLATFORM_DEVICES
> > diff --git a/drivers/platform/arm64/Makefile b/drivers/platform/arm64/Makefile
> > index 4fcc9855579b..b2ae9114fdd8 100644
> > --- a/drivers/platform/arm64/Makefile
> > +++ b/drivers/platform/arm64/Makefile
> > @@ -6,3 +6,4 @@
> >   #
> >   obj-$(CONFIG_EC_ACER_ASPIRE1)	+= acer-aspire1-ec.o
> > +obj-$(CONFIG_EC_LENOVO_YOGA_C630) += lenovo-yoga-c630.o
> > diff --git a/drivers/platform/arm64/lenovo-yoga-c630.c b/drivers/platform/arm64/lenovo-yoga-c630.c
> > new file mode 100644
> > index 000000000000..3d1d5acde807
> > --- /dev/null
> > +++ b/drivers/platform/arm64/lenovo-yoga-c630.c
> > @@ -0,0 +1,279 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * Copyright (c) 2022-2024, Linaro Ltd
> > + * Authors:
> > + *    Bjorn Andersson
> > + *    Dmitry Baryshkov
> > + */
> > +#include <linux/auxiliary_bus.h>
> > +#include <linux/i2c.h>
> > +#include <linux/module.h>
> > +#include <linux/notifier.h>
> > +#include <linux/platform_data/lenovo-yoga-c630.h>
> > +
> > +#define LENOVO_EC_RESPONSE_REG		0x01
> > +#define LENOVO_EC_REQUEST_REG		0x02
> > +
> > +#define LENOVO_EC_UCSI_WRITE		0x20
> > +#define LENOVO_EC_UCSI_READ		0x21
> > +
> > +#define LENOVO_EC_READ_REG		0xb0
> > +#define LENOVO_EC_REQUEST_NEXT_EVENT	0x84
> > +
> > +struct yoga_c630_ec {
> > +	struct i2c_client *client;
> > +	struct mutex lock;
> > +	struct blocking_notifier_head notifier_list;
> > +};
> > +
> > +static int yoga_c630_ec_request(struct yoga_c630_ec *ec, u8 *req, size_t req_len,
> > +				u8 *resp, size_t resp_len)
> > +{
> > +	int ret;
> > +
> > +	WARN_ON(!mutex_is_locked(&ec->lock));
> > +
> > +	ret = i2c_smbus_write_i2c_block_data(ec->client, LENOVO_EC_REQUEST_REG,
> > +					     req_len, req);
> > +	if (ret < 0)
> > +		return ret;
> > +
> > +	return i2c_smbus_read_i2c_block_data(ec->client, LENOVO_EC_RESPONSE_REG,
> > +					     resp_len, resp);
> > +}
> > +
> > +int yoga_c630_ec_read8(struct yoga_c630_ec *ec, u8 addr)
> > +{
> > +	u8 req[2] = { LENOVO_EC_READ_REG, };
> > +	int ret;
> > +	u8 val;
> > +
> > +	mutex_lock(&ec->lock);
> > +	req[1] = addr;
> > +	ret = yoga_c630_ec_request(ec, req, sizeof(req), &val, 1);
> > +	mutex_unlock(&ec->lock);
> > +
> > +	return ret < 0 ? ret : val;
> > +}
> > +EXPORT_SYMBOL_GPL(yoga_c630_ec_read8);
> > +
> > +int yoga_c630_ec_read16(struct yoga_c630_ec *ec, u8 addr)
> > +{
> > +	u8 req[2] = { LENOVO_EC_READ_REG, };
> > +	int ret;
> > +	u8 msb;
> > +	u8 lsb;
> > +
> > +	mutex_lock(&ec->lock);
> > +
> > +	req[1] = addr;
> > +	ret = yoga_c630_ec_request(ec, req, sizeof(req), &lsb, 1);
> > +	if (ret < 0)
> > +		goto out;
> > +
> > +	req[1] = addr + 1;
> > +	ret = yoga_c630_ec_request(ec, req, sizeof(req), &msb, 1);
> > +
> > +out:
> > +	mutex_unlock(&ec->lock);
> > +
> > +	return ret < 0 ? ret : msb << 8 | lsb;
> > +}
> > +EXPORT_SYMBOL_GPL(yoga_c630_ec_read16);
> > +
> > +u16 yoga_c630_ec_ucsi_get_version(struct yoga_c630_ec *ec)
> > +{
> > +	u8 req[3] = { 0xb3, 0xf2, 0x20};
> 
> You have a define above for the read_reg and write_reg commands, could you
> not define 0xb3 as LENOVO_EC_GET_VERSION ?
> 
> All of the other commands here seem to have a named define.

Because unlike other registers it is not clear what other use cases does
0xb3 support

> 
> > +	int ret;
> > +	u8 msb;
> > +	u8 lsb;
> > +
> > +	mutex_lock(&ec->lock);
> > +	ret = yoga_c630_ec_request(ec, req, sizeof(req), &lsb, 1);
> > +	if (ret < 0)
> > +		goto out;
> > +
> > +	req[2]++;
> 
> why not set reg[2] = 0x21;

ack

> 
> also is req[2] some kind of address ?

Unfortunately no idea. This is totally based on the AML code in DSDT. I
have no documentation on the EC or its programming interface.

> 
> > +	ret = yoga_c630_ec_request(ec, req, sizeof(req), &msb, 1);
> > +
> > +out:
> > +	mutex_unlock(&ec->lock);
> > +
> > +	return ret < 0 ? ret : msb << 8 | lsb;
> > +}
> > +EXPORT_SYMBOL_GPL(yoga_c630_ec_ucsi_get_version);
> > +
> > +int yoga_c630_ec_ucsi_write(struct yoga_c630_ec *ec,
> > +			    const u8 req[YOGA_C630_UCSI_WRITE_SIZE])
> > +{
> > +	int ret;
> > +
> > +	mutex_lock(&ec->lock);
> > +	ret = i2c_smbus_write_i2c_block_data(ec->client, LENOVO_EC_UCSI_WRITE,
> > +					     YOGA_C630_UCSI_WRITE_SIZE, req);
> > +	mutex_unlock(&ec->lock);
> > +
> > +	return ret < 0 ? ret : 0;
> > +}
> > +EXPORT_SYMBOL_GPL(yoga_c630_ec_ucsi_write);
> > +
> > +int yoga_c630_ec_ucsi_read(struct yoga_c630_ec *ec,
> > +			   u8 resp[YOGA_C630_UCSI_READ_SIZE])
> > +{
> > +	int ret;
> > +
> > +	mutex_lock(&ec->lock);
> > +	ret = i2c_smbus_read_i2c_block_data(ec->client, LENOVO_EC_UCSI_READ,
> > +					    YOGA_C630_UCSI_READ_SIZE, resp);
> > +	mutex_unlock(&ec->lock);
> > +
> > +	return ret < 0 ? ret : 0;
> > +}
> > +EXPORT_SYMBOL_GPL(yoga_c630_ec_ucsi_read);
> > +
> > +static irqreturn_t yoga_c630_ec_intr(int irq, void *data)
> > +{
> > +	u8 req[] = { LENOVO_EC_REQUEST_NEXT_EVENT };
> > +	struct yoga_c630_ec *ec = data;
> > +	u8 event;
> > +	int ret;
> > +
> > +	mutex_lock(&ec->lock);
> > +	ret = yoga_c630_ec_request(ec, req, sizeof(req), &event, 1);
> > +	mutex_unlock(&ec->lock);
> > +	if (ret < 0)
> > +		return IRQ_HANDLED;
> > +
> > +	pr_info("NOTIFY %x\n", event);
> 
> why not dev_info() ?

Argh, debugging code. I should drop it.

-- 
With best wishes
Dmitry