Re: [PATCH v10 2/2] usb: typec: ucsi: add support for Cypress CCGx

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On 2018-09-08 02:09, Ajay Gupta wrote:
> Latest NVIDIA GPU cards have a Cypress CCGx Type-C controller
> over I2C interface.
> 
> This UCSI I2C driver uses I2C bus driver interface for communicating
> with Type-C controller.
> 
> Signed-off-by: Ajay Gupta <ajayg@xxxxxxxxxx>
> Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
> Acked-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
> ---
> Changes from v1 -> v2
> 	Fixed identation in drivers/usb/typec/ucsi/Kconfig
> Changes from v2 -> v3
> 	Fixed most of comments from Heikki
> 	Rename ucsi_i2c_ccg.c -> ucsi_ccg.c
> Changes from v3 -> v4
> 	Fixed comments from Andy
> Changes from v4 -> v5
> 	Fixed comments from Andy
> Changes from v5 -> v6
> 	Fixed review comments from Greg 
> Changes from v6 -> v7
> 	None
> Changes from v7 -> v8
> 	Fixed review comments from Peter 
> 	- Removed empty STOP message
> 	- Using stack memory for i2c_transfer()
> Changes from v8 -> v9
> 	None
> Changes from v9 -> v10
> 	Fixed review comments from Peter 
> 	- Use UCSI macros
> 	- Cleanups
> 
>  drivers/usb/typec/ucsi/Kconfig    |  10 ++
>  drivers/usb/typec/ucsi/Makefile   |   2 +
>  drivers/usb/typec/ucsi/ucsi_ccg.c | 324 ++++++++++++++++++++++++++++++++++++++
>  3 files changed, 336 insertions(+)
>  create mode 100644 drivers/usb/typec/ucsi/ucsi_ccg.c
> 
> diff --git a/drivers/usb/typec/ucsi/Kconfig b/drivers/usb/typec/ucsi/Kconfig
> index e36d6c7..7811888 100644
> --- a/drivers/usb/typec/ucsi/Kconfig
> +++ b/drivers/usb/typec/ucsi/Kconfig
> @@ -23,6 +23,16 @@ config TYPEC_UCSI
>  
>  if TYPEC_UCSI
>  
> +config UCSI_CCG
> +	tristate "UCSI Interface Driver for Cypress CCGx"
> +	depends on I2C
> +	help
> +	  This driver enables UCSI support on platforms that expose a
> +	  Cypress CCGx Type-C controller over I2C interface.
> +
> +	  To compile the driver as a module, choose M here: the module will be
> +	  called ucsi_ccg.
> +
>  config UCSI_ACPI
>  	tristate "UCSI ACPI Interface Driver"
>  	depends on ACPI
> diff --git a/drivers/usb/typec/ucsi/Makefile b/drivers/usb/typec/ucsi/Makefile
> index 7afbea5..2f4900b 100644
> --- a/drivers/usb/typec/ucsi/Makefile
> +++ b/drivers/usb/typec/ucsi/Makefile
> @@ -8,3 +8,5 @@ typec_ucsi-y			:= ucsi.o
>  typec_ucsi-$(CONFIG_TRACING)	+= trace.o
>  
>  obj-$(CONFIG_UCSI_ACPI)		+= ucsi_acpi.o
> +
> +obj-$(CONFIG_UCSI_CCG)		+= ucsi_ccg.o
> diff --git a/drivers/usb/typec/ucsi/ucsi_ccg.c b/drivers/usb/typec/ucsi/ucsi_ccg.c
> new file mode 100644
> index 0000000..c346e6a
> --- /dev/null
> +++ b/drivers/usb/typec/ucsi/ucsi_ccg.c
> @@ -0,0 +1,324 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * UCSI driver for Cypress CCGx Type-C controller
> + *
> + * Copyright (C) 2017-2018 NVIDIA Corporation. All rights reserved.
> + * Author: Ajay Gupta <ajayg@xxxxxxxxxx>
> + *
> + * Some code borrowed from drivers/usb/typec/ucsi/ucsi_acpi.c
> + */
> +#include <linux/acpi.h>
> +#include <linux/delay.h>
> +#include <linux/i2c.h>
> +#include <linux/module.h>
> +#include <linux/pci.h>
> +#include <linux/platform_device.h>
> +
> +#include <asm/unaligned.h>
> +#include "ucsi.h"
> +
> +struct ucsi_ccg {
> +	struct device *dev;
> +	struct ucsi *ucsi;
> +	struct ucsi_ppm ppm;
> +	struct i2c_client *client;
> +	int irq;
> +};
> +
> +#define CCGX_I2C_RAB_DEVICE_MODE			0x00
> +#define CCGX_I2C_RAB_READ_SILICON_ID			0x2
> +#define CCGX_I2C_RAB_INTR_REG				0x06
> +#define CCGX_I2C_RAB_FW1_VERSION			0x28
> +#define CCGX_I2C_RAB_FW2_VERSION			0x20
> +#define CCGX_I2C_RAB_UCSI_CONTROL			0x39
> +#define CCGX_I2C_RAB_UCSI_CONTROL_START			BIT(0)
> +#define CCGX_I2C_RAB_UCSI_CONTROL_STOP			BIT(1)
> +#define CCGX_I2C_RAB_RESPONSE_REG			0x7E
> +#define CCGX_I2C_RAB_UCSI_DATA_BLOCK(offset)	(0xf000 | ((offset) & 0xff))
> +
> +#define USBC_VERSION_OFFSET	(0x0)
> +#define USBC_VERSION_SIZE	(2)
> +#define USBC_CCI_OFFSET		(0x4)
> +#define USBC_CCI_SIZE		(4)
> +#define USBC_CONTROL_OFFSET	(0x8)
> +#define USBC_CONTROL_SIZE	(8)
> +#define USBC_MSG_IN_OFFSET	(0x10)
> +#define USBC_MSG_IN_SIZE	(16)
> +#define USBC_MSG_OUT_OFFSET	(0x20)
> +#define USBC_MSG_OUT_SIZE	(16)
> +
> +static int ccg_read(struct ucsi_ccg *uc, u16 rab, u8 *data, u32 len)
> +{
> +	struct i2c_client *client = uc->client;
> +	unsigned char buf[2];
> +	struct i2c_msg msgs[] = {
> +		{
> +			.addr	= client->addr,
> +			.flags  = 0x0,
> +			.len	= 0x2,

sizeof(buf)?

> +			.buf	= buf,
> +		},
> +		{
> +			.addr	= client->addr,
> +			.flags  = I2C_M_RD,
> +			.buf	= data,
> +		},
> +	};
> +	u32 rlen, rem_len = len;
> +	int status;
> +

If your target I2C adapter had supported larger reads, this would have
been a single xfer instead of the loop, correct? I think this deserves
a comment, and perhaps e.g. the eeprom drivers should be examined to
see how they handle deficient I2C adapters (there is a module_param
named io_limit in the at24 driver). Because it is a little bit sad to
penalise all users just because you have an adapter with limitations.
Or is this driver tied to that adapter?

Anyway, I'm satisfied with a comment, as I don't care all that much.

> +	while (rem_len > 0) {
> +		msgs[1].buf = &data[len - rem_len];
> +		rlen = min_t(u16, rem_len, 4);
> +		msgs[1].len = rlen;
> +		put_unaligned_le16(rab, buf);
> +		status = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
> +		if (status < 0) {
> +			dev_err(uc->dev, "i2c_transfer failed %d\n", status);
> +			return status;
> +		}
> +		rab += rlen;
> +		rem_len -= rlen;
> +	}
> +
> +	return 0;
> +}
> +
> +static int ccg_write(struct ucsi_ccg *uc, u16 rab, u8 *data, u32 len)
> +{
> +	struct i2c_client *client = uc->client;
> +	unsigned char buf[2];
> +	struct i2c_msg msgs[] = {
> +		{
> +			.addr	= client->addr,
> +			.flags  = 0x0,
> +			.len	= 0x2,

sizeof(buf)?

> +			.buf	= buf,
> +		},
> +		{
> +			.addr	= client->addr,
> +			.flags  = 0x0,
> +			.buf	= data,
> +			.len	= len,
> +		},
> +	};
> +	int status;
> +
> +	put_unaligned_le16(rab, buf);
> +	status = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
> +	if (status < 0) {
> +		dev_err(uc->dev, "i2c_transfer failed %d\n", status);
> +		return status;
> +	}
> +
> +	return 0;
> +}
> +
> +static int ucsi_ccg_init(struct ucsi_ccg *uc)
> +{
> +	struct device *dev = uc->dev;
> +	unsigned int count = 10;
> +	u8 data[64];
> +	int status;
> +
> +	status = ccg_read(uc, CCGX_I2C_RAB_DEVICE_MODE, data, sizeof(data));
> +	if (status < 0)
> +		return status;
> +
> +	dev_dbg(dev, "Silicon id %2ph", data + CCGX_I2C_RAB_READ_SILICON_ID);
> +	dev_dbg(dev, "FW1 version %8ph\n", data + CCGX_I2C_RAB_FW1_VERSION);
> +	dev_dbg(dev, "FW2 version %8ph\n", data + CCGX_I2C_RAB_FW2_VERSION);
> +
> +	data[0] = CCGX_I2C_RAB_UCSI_CONTROL_STOP;
> +	status = ccg_write(uc, CCGX_I2C_RAB_UCSI_CONTROL, data, 0x1);
> +	if (status < 0)
> +		return status;
> +
> +	data[0] = CCGX_I2C_RAB_UCSI_CONTROL_START;
> +	status = ccg_write(uc, CCGX_I2C_RAB_UCSI_CONTROL, data, 0x1);
> +	if (status < 0)
> +		return status;
> +
> +	/*
> +	 * Flush CCGx RESPONSE queue by acking interrupts
> +	 * - above ucsi control register write will push response
> +	 * which must be flushed
> +	 * - affects f/w update which reads response register
> +	 */
> +	data[0] = 0xff;
> +	do {
> +		status = ccg_write(uc, CCGX_I2C_RAB_INTR_REG, data, 0x1);
> +		if (status < 0)
> +			return status;
> +
> +		usleep_range(10000, 11000);
> +
> +		status = ccg_read(uc, CCGX_I2C_RAB_INTR_REG, data, 0x1);
> +		if (status < 0)
> +			return status;
> +	} while ((data[0] != 0x00) && count--);
> +
> +	return 0;
> +}
> +
> +static int ucsi_ccg_send_data(struct ucsi_ccg *uc)
> +{
> +	unsigned char buf1[USBC_MSG_OUT_SIZE];
> +	unsigned char buf2[USBC_CONTROL_SIZE];
> +	int status;
> +	u16 rab;
> +
> +	memcpy(buf1, (u8 *)(uc->ppm.data) + USBC_MSG_OUT_OFFSET, sizeof(buf1));
> +	memcpy(buf2, (u8 *)(uc->ppm.data) + USBC_CONTROL_OFFSET, sizeof(buf2));

Hmm, now that I see what this function does, instead of just seeing a bunch
of magic numbers, I wonder why you make copies instead of feeding the correct
section of the ppm.data buffer directly to ccg_write, like you do below for
recv?

> +
> +	rab = CCGX_I2C_RAB_UCSI_DATA_BLOCK(USBC_MSG_OUT_OFFSET);
> +	status = ccg_write(uc, rab, buf1, sizeof(buf1));
> +	if (status < 0)
> +		return status;
> +
> +	rab = CCGX_I2C_RAB_UCSI_DATA_BLOCK(USBC_CONTROL_OFFSET);
> +	return ccg_write(uc, rab, buf2, sizeof(buf2));
> +}
> +
> +static int ucsi_ccg_recv_data(struct ucsi_ccg *uc)
> +{
> +	u8 *ppm = (u8 *)uc->ppm.data;
> +	int status;
> +	u16 rab;
> +
> +	rab = CCGX_I2C_RAB_UCSI_DATA_BLOCK(USBC_CCI_OFFSET);
> +	status = ccg_read(uc, rab, ppm + USBC_CCI_OFFSET, USBC_CCI_SIZE);
> +	if (status < 0)
> +		return status;
> +
> +	rab = CCGX_I2C_RAB_UCSI_DATA_BLOCK(USBC_MSG_IN_OFFSET);
> +	return ccg_read(uc, rab, ppm + USBC_MSG_IN_OFFSET, USBC_MSG_IN_SIZE);
> +}
> +
> +static int ucsi_ccg_ack_interrupt(struct ucsi_ccg *uc)
> +{
> +	int status;
> +	unsigned char buf[1] = {0x0};

The initializer can be dropped.

> +
> +	status = ccg_read(uc, CCGX_I2C_RAB_INTR_REG, buf, 0x1);

sizeof(buf)?

> +	if (status < 0)
> +		return status;
> +
> +	return ccg_write(uc, CCGX_I2C_RAB_INTR_REG, buf, 0x1);

sizeof(buf)?

> +}
> +
> +static int ucsi_ccg_sync(struct ucsi_ppm *ppm)
> +{
> +	struct ucsi_ccg *uc = container_of(ppm, struct ucsi_ccg, ppm);
> +	int status;
> +
> +	status = ucsi_ccg_recv_data(uc);
> +	if (status < 0)
> +		return status;
> +
> +	/* ack interrupt to allow next command to run */
> +	return ucsi_ccg_ack_interrupt(uc);
> +}
> +
> +static int ucsi_ccg_cmd(struct ucsi_ppm *ppm, struct ucsi_control *ctrl)
> +{
> +	struct ucsi_ccg *uc = container_of(ppm, struct ucsi_ccg, ppm);
> +
> +	ppm->data->ctrl.raw_cmd = ctrl->raw_cmd;
> +	return ucsi_ccg_send_data(uc);
> +}
> +
> +static irqreturn_t ccg_irq_handler(int irq, void *data)
> +{
> +	struct ucsi_ccg *uc = data;
> +
> +	ucsi_notify(uc->ucsi);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int ucsi_ccg_probe(struct i2c_client *client,
> +			  const struct i2c_device_id *id)
> +{
> +	struct device *dev = &client->dev;
> +	struct ucsi_ccg *uc;
> +	int status;
> +	u16 rab;
> +
> +	uc = devm_kzalloc(dev, sizeof(*uc), GFP_KERNEL);
> +	if (!uc)
> +		return -ENOMEM;
> +
> +	uc->ppm.data = devm_kzalloc(dev, sizeof(struct ucsi_data), GFP_KERNEL);
> +	if (!uc->ppm.data)
> +		return -ENOMEM;

Wait a minute, ppm.data is allocated as a struct? And it's __packed! So, it's
clearly intended to match something real. I didn't notice that before,
but that means that all the new offsets and sizes defined in v10 are available
with offsetof() and sizeof() which would be much neater than a bunch of
defines. Sorry for not catching this earlier!

See below for an example.

> +
> +	uc->ppm.cmd = ucsi_ccg_cmd;
> +	uc->ppm.sync = ucsi_ccg_sync;
> +	uc->dev = dev;
> +	uc->client = client;
> +
> +	/* reset ccg device and initialize ucsi */
> +	status = ucsi_ccg_init(uc);
> +	if (status < 0) {
> +		dev_err(uc->dev, "ucsi_ccg_init failed - %d\n", status);
> +		return status;
> +	}
> +
> +	uc->irq = client->irq;
> +
> +	status = devm_request_threaded_irq(dev, uc->irq, NULL, ccg_irq_handler,
> +					   IRQF_ONESHOT | IRQF_TRIGGER_HIGH,
> +					   dev_name(dev), uc);
> +	if (status < 0) {
> +		dev_err(uc->dev, "request_threaded_irq failed - %d\n", status);
> +		return status;
> +	}
> +
> +	uc->ucsi = ucsi_register_ppm(dev, &uc->ppm);
> +	if (IS_ERR(uc->ucsi)) {
> +		dev_err(uc->dev, "ucsi_register_ppm failed\n");
> +		return PTR_ERR(uc->ucsi);
> +	}
> +
> +	rab = CCGX_I2C_RAB_UCSI_DATA_BLOCK(USBC_VERSION_OFFSET);
> +	status = ccg_read(uc, rab, (u8 *)(uc->ppm.data) + USBC_VERSION_OFFSET,
> +			  USBC_VERSION_SIZE);

E.g.
	rab = CCGX_I2C_RAB_UCSI_DATA_BLOCK(offsetof(struct ucsi_data, version));
	status = ccg_read(uc, rab, (u8 *)&uc->ppm.data->version,
			  sizeof(uc->ppm.data->version));

Hmm, but this highlights that you are not doing any endian conversion of
the fields in that struct as you read/write it. Do you need to in case
you have an endian mismatch?

Cheers,
Peter

> +	if (status < 0) {
> +		ucsi_unregister_ppm(uc->ucsi);
> +		return status;
> +	}
> +
> +	i2c_set_clientdata(client, uc);
> +	return 0;
> +}
> +
> +static int ucsi_ccg_remove(struct i2c_client *client)
> +{
> +	struct ucsi_ccg *uc = i2c_get_clientdata(client);
> +
> +	ucsi_unregister_ppm(uc->ucsi);
> +
> +	return 0;
> +}
> +
> +static const struct i2c_device_id ucsi_ccg_device_id[] = {
> +	{"ccgx-ucsi", 0},
> +	{}
> +};
> +MODULE_DEVICE_TABLE(i2c, ucsi_ccg_device_id);
> +
> +static struct i2c_driver ucsi_ccg_driver = {
> +	.driver = {
> +		.name = "ucsi_ccg",
> +	},
> +	.probe = ucsi_ccg_probe,
> +	.remove = ucsi_ccg_remove,
> +	.id_table = ucsi_ccg_device_id,
> +};
> +
> +module_i2c_driver(ucsi_ccg_driver);
> +
> +MODULE_AUTHOR("Ajay Gupta <ajayg@xxxxxxxxxx>");
> +MODULE_DESCRIPTION("UCSI driver for Cypress CCGx Type-C controller");
> +MODULE_LICENSE("GPL v2");
> 




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