Re: [RFC V1 3/8] smi2021: Add smi2021_i2c.c

[Hans Verkuil]

On Thu March 14 2013 15:06:59 Jon Arne JÃrgensen wrote:
> This file is responsible for registering the device
> with the kernel i2c subsystem.
> v4l2 talks to the saa7113 chip of the device via i2c.
> 
> Signed-off-by: Jon Arne JÃrgensen <jonarne@xxxxxxxxxx>
> ---
>  drivers/media/usb/smi2021/smi2021_i2c.c | 160 ++++++++++++++++++++++++++++++++
>  1 file changed, 160 insertions(+)
>  create mode 100644 drivers/media/usb/smi2021/smi2021_i2c.c
> 
> diff --git a/drivers/media/usb/smi2021/smi2021_i2c.c b/drivers/media/usb/smi2021/smi2021_i2c.c
> new file mode 100644
> index 0000000..5b6f3f5
> --- /dev/null
> +++ b/drivers/media/usb/smi2021/smi2021_i2c.c
> @@ -0,0 +1,160 @@
> +/*******************************************************************************
> + * smi2021_i2c.c                                                               *
> + *                                                                             *
> + * USB Driver for SMI2021 - EasyCAP                                            *
> + * USB ID 1c88:003c                                                            *
> + *                                                                             *
> + * *****************************************************************************
> + *
> + * Copyright 2011-2013 Jon Arne JÃrgensen
> + * <jonjon.arnearne--a.t--gmail.com>
> + *
> + * Copyright 2011, 2012 Tony Brown, Michal Demin, Jeffry Johnston
> + *
> + * This file is part of SMI2021
> + * http://code.google.com/p/easycap-somagic-linux/
> + *
> + * This program is free software: you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation, either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, see <http://www.gnu.org/licenses/>.
> + *
> + * This driver is heavily influensed by the STK1160 driver.
> + * Copyright (C) 2012 Ezequiel Garcia
> + * <elezegarcia--a.t--gmail.com>
> + *
> + */
> +
> +#include "smi2021.h"
> +
> +/* The device will not return the chip_name on address 0x00.
> + * But the saa7115 i2c driver needs the chip id to match "f7113"
> + * if we want to use it,
> + * so we have to fake the return of this value
> + */
> +
> +static char chip_id[] = { 'x', 255, 55, 49, 49, 115, 0 };
> +static int id_ptr;

Don't do this! Instead modify saa7115.c and add a new chip_id (the name of
this saa7113 clone) and specify that in v4l2_i2c_new_subdev instead of "saa7113".
The saa7115.c driver should skip the chip ID test if that name is specified.

Then you don't need this hack anymore and everything will look much cleaner.

> +
> +static unsigned int i2c_debug;
> +module_param(i2c_debug, int, 0644);
> +MODULE_PARM_DESC(i2c_debug, "enable debug messages [i2c]");
> +
> +#define dprint_i2c(fmt, args...)					\
> +do {									\
> +	if (i2c_debug)							\
> +		pr_debug("smi2021[i2c]::%s: " fmt, __func__, ##args);	\
> +} while (0)
> +
> +
> +static int i2c_xfer(struct i2c_adapter *i2c_adap,
> +				struct i2c_msg msgs[], int num)
> +{
> +	struct smi2021_dev *dev = i2c_adap->algo_data;
> +
> +	switch (num) {
> +	case 2: { /* Read reg */
> +		if (msgs[0].len != 1 || msgs[1].len != 1) {
> +			dprint_i2c("both messages must be 1 byte\n");
> +			goto err_out;
> +
> +		if ((msgs[1].flags & I2C_M_RD) != I2C_M_RD)
> +			dprint_i2c("last message should have rd flag\n");
> +			goto err_out;
> +		}
> +
> +		if (msgs[0].buf[0] == 0) {
> +			msgs[1].buf[0] = chip_id[id_ptr];
> +			if (chip_id[id_ptr] != 0)
> +				id_ptr += 1;
> +		} else {
> +			smi2021_read_reg(dev, msgs[0].addr, msgs[0].buf[0],
> +						msgs[1].buf);
> +		}
> +		break;
> +	}
> +	case 1: { /* Write reg */
> +		if (msgs[0].len == 0) {
> +			break;
> +		} else if (msgs[0].len != 2) {
> +			dprint_i2c("unsupported len\n");
> +			goto err_out;
> +		}
> +		if (msgs[0].buf[0] == 0) {
> +			/* We don't handle writing to addr 0x00 */
> +			break;
> +		}
> +
> +		smi2021_write_reg(dev, msgs[0].addr, msgs[0].buf[0],
> +						msgs[0].buf[1]);
> +		break;
> +	}
> +	default: {
> +		dprint_i2c("driver can only handle 1 or 2 messages\n");
> +		goto err_out;
> +	}
> +	}
> +	return num;
> +
> +err_out:
> +	return -EOPNOTSUPP;
> +}
> +
> +static u32 functionality(struct i2c_adapter *adap)
> +{
> +	return I2C_FUNC_SMBUS_EMUL;
> +}
> +
> +static struct i2c_algorithm algo = {
> +	.master_xfer = i2c_xfer,
> +	.functionality = functionality,
> +};
> +
> +static struct i2c_adapter adap_template = {
> +	.owner = THIS_MODULE,
> +	.name = "smi2021_easycap_dc60",
> +	.algo = &algo,
> +};
> +
> +static struct i2c_client client_template = {
> +	.name = "smi2021 internal",
> +};
> +
> +int smi2021_i2c_register(struct smi2021_dev *dev)
> +{
> +	int rc;
> +
> +	id_ptr = 0;
> +
> +	dev->i2c_adap = adap_template;
> +	dev->i2c_adap.dev.parent = dev->dev;
> +	strcpy(dev->i2c_adap.name, "smi2021");
> +	dev->i2c_adap.algo_data = dev;
> +
> +	i2c_set_adapdata(&dev->i2c_adap, &dev->v4l2_dev);
> +
> +	rc = i2c_add_adapter(&dev->i2c_adap);
> +	if (rc < 0) {
> +		smi2021_err("can't add i2c adapter, errno: %d\n", rc);
> +		return rc;
> +	}
> +
> +	dev->i2c_client = client_template;
> +	dev->i2c_client.adapter = &dev->i2c_adap;
> +
> +	return 0;
> +}
> +
> +int smi2021_i2c_unregister(struct smi2021_dev *dev)
> +{
> +	i2c_del_adapter(&dev->i2c_adap);
> +	return 0;
> +}
> 

Regards,

	Hans
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