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

[Ajay Gupta <ajayg@nvidia.com>]

Hi Peter,

> > 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@nvidia.com>
> > Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
> > Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> > ---
> > 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@nvidia.com>
> > + *
> > + * 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)?
ok
> 
> > +			.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.
I am thinking of moving the loop to the i2c driver. 
 
> > +	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)?
ok
> 
> > +			.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?
Ok, will fix.
> 
> > +
> > +	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.
ok
> 
> > +
> > +	status = ccg_read(uc, CCGX_I2C_RAB_INTR_REG, buf, 0x1);
> 
> sizeof(buf)?
ok
> 
> > +	if (status < 0)
> > +		return status;
> > +
> > +	return ccg_write(uc, CCGX_I2C_RAB_INTR_REG, buf, 0x1);
> 
> sizeof(buf)?
ok
> 
> > +}
> > +
> > +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.
Sure.
> 
> > +
> > +	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?
Looks like don't need it. I have tested it and it works as is.

Thanks
Ajay

--
nvpublic
--
> 
> 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@nvidia.com>");
> > +MODULE_DESCRIPTION("UCSI driver for Cypress CCGx Type-C controller");
> > +MODULE_LICENSE("GPL v2");
> >