[v13,2/2] usb: typec: ucsi: add support for Cypress CCGx

[Ajay Gupta <ajayg@nvidia.com>]

Hi Heikki and Andy
[...]
> > > Shouldn't you return -ETIMEDOUT if count == 0?
> > Yes. Good catch. Does the below fix looks ok?
> >
> >         do {
> >                 status = ccg_write(uc, CCGX_RAB_INTR_REG, &data, sizeof(data));
> >                 if (status < 0)
> >                         return status;
> >
> >                 usleep_range(10000, 11000);
> >
> >                 status = ccg_read(uc, CCGX_RAB_INTR_REG, &data, sizeof(data));
> >                 if (status < 0)
> >                         return status;
> >
> >                 if (!data)
> >                         return 0;
> >         } while (data && count--);
> 
> Doesn't that condition break out of the loop immediately?
How? I didn't get your point? We want to break out when data is
zero (interrupt status cleared).

> > Ah, I see, but why you not reorganize it to put this into do-while loop?
We actually need to check data after reading it so will reorganize accordingly.
do {
	read
	check for data and break out if (!data)
	write
	sleep
} while (--count);

Thanks
Ajay
-nvpublic
> >         return -ETIMEDOUT;
> >
> > > Something like:
> > >
> > >         ...
> > >         while (count--)
> > > 		status = ccg_read(uc, CCGX_RAB_INTR_REG, &data,
> sizeof(data));
> > > 		if (status < 0)
> > > 			return status;
> > >                 if (!data)
> > >                         return 0;
> > > 	}
> > >
> > >         return -ETIMEDOUT;
> > >
> > > Or does the count of 10 have some specific meaning?
> > >
> > > > +}
> > > > +
> > > > +static int ucsi_ccg_send_data(struct ucsi_ccg *uc) {
> > > > +	u8 *ppm = (u8 *)uc->ppm.data;
> > > > +	int status;
> > > > +	u16 rab;
> > > > +
> > > > +	rab = CCGX_RAB_UCSI_DATA_BLOCK(offsetof(struct ucsi_data,
> > > message_out));
> > > > +	status = ccg_write(uc, rab, ppm +
> > > > +			   offsetof(struct ucsi_data, message_out),
> > > > +			   sizeof(uc->ppm.data->message_out));
> > > > +	if (status < 0)
> > > > +		return status;
> > > > +
> > > > +	rab = CCGX_RAB_UCSI_DATA_BLOCK(offsetof(struct ucsi_data, ctrl));
> > > > +	return ccg_write(uc, rab, ppm + offsetof(struct ucsi_data, ctrl),
> > > > +			 sizeof(uc->ppm.data->ctrl));
> > > > +}
> > > > +
> > > > +static int ucsi_ccg_recv_data(struct ucsi_ccg *uc) {
> > > > +	u8 *ppm = (u8 *)uc->ppm.data;
> > > > +	int status;
> > > > +	u16 rab;
> > > > +
> > > > +	rab = CCGX_RAB_UCSI_DATA_BLOCK(offsetof(struct ucsi_data, cci));
> > > > +	status = ccg_read(uc, rab, ppm + offsetof(struct ucsi_data, cci),
> > > > +			  sizeof(uc->ppm.data->cci));
> > > > +	if (status < 0)
> > > > +		return status;
> > > > +
> > > > +	rab = CCGX_RAB_UCSI_DATA_BLOCK(offsetof(struct ucsi_data,
> > > message_in));
> > > > +	return ccg_read(uc, rab, ppm + offsetof(struct ucsi_data, message_in),
> > > > +			sizeof(uc->ppm.data->message_in));
> > > > +}
> > > > +
> > > > +static int ucsi_ccg_ack_interrupt(struct ucsi_ccg *uc) {
> > > > +	int status;
> > > > +	unsigned char data;
> > > > +
> > > > +	status = ccg_read(uc, CCGX_RAB_INTR_REG, &data, sizeof(data));
> > > > +	if (status < 0)
> > > > +		return status;
> > > > +
> > > > +	return ccg_write(uc, CCGX_RAB_INTR_REG, &data, sizeof(data)); }
> > > > +
> > > > +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;
> > > > +
> > > > +	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_RAB_UCSI_DATA_BLOCK(offsetof(struct ucsi_data,
> > > version));
> > > > +	status = ccg_read(uc, rab, (u8 *)(uc->ppm.data) +
> > > > +			  offsetof(struct ucsi_data, version),
> > > > +			  sizeof(uc->ppm.data->version));
> > > > +	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");
> > >
> > > I'm still worried about how this driver works on other platforms. It
> > > just looks like you have written ccg_read/write() functions for only your
> I2C host.
> > >
> > > I would feel much more comfortable with this if you for example used
> > > those
> > > i2c_smbus_read/write*() helpers instead of raw i2c_transfer().
> > > I would expect them to force you to write your i2c host driver, as
> > > well as this driver, in a more generic fashion.
> >
> > I2c_smbus_read/write*() will not work with Cypress CCGx controller
> > since CCGx requires 2 byte of command for any read/write transaction.
> > I2c_smbus_read/write*() APIs support only 1 byte of command.
> 
> OK, got it.
> 
> 
> thanks,
> 
> --
> heikki