rtc-x1205.c

linux 内核源代码

	/* atr is a two's complement value on 6 bits,
	 * perform sign extension. The formula is
	 * Catr = (atr * 0.25pF) + 11.00pF.
	 */
	if (atr & 0x20)
		atr |= 0xC0;

	dev_dbg(&client->dev, "%s: raw atr=%x (%d)\n", __FUNCTION__, atr, atr);

	*trim = (atr * 250) + 11000;

	dev_dbg(&client->dev, "%s: real=%d\n", __FUNCTION__, *trim);

	return 0;
}

struct x1205_limit
{
	unsigned char reg, mask, min, max;
};

static int x1205_validate_client(struct i2c_client *client)
{
	int i, xfer;

	/* Probe array. We will read the register at the specified
	 * address and check if the given bits are zero.
	 */
	static const unsigned char probe_zero_pattern[] = {
		/* register, mask */
		X1205_REG_SR,	0x18,
		X1205_REG_DTR,	0xF8,
		X1205_REG_ATR,	0xC0,
		X1205_REG_INT,	0x18,
		X1205_REG_0,	0xFF,
	};

	static const struct x1205_limit probe_limits_pattern[] = {
		/* register, mask, min, max */
		{ X1205_REG_Y2K,	0xFF,	19,	20	},
		{ X1205_REG_DW,		0xFF,	0,	6	},
		{ X1205_REG_YR,		0xFF,	0,	99	},
		{ X1205_REG_MO,		0xFF,	0,	12	},
		{ X1205_REG_DT,		0xFF,	0,	31	},
		{ X1205_REG_HR,		0x7F,	0,	23	},
		{ X1205_REG_MN,		0xFF,	0,	59	},
		{ X1205_REG_SC,		0xFF,	0,	59	},
		{ X1205_REG_Y2K1,	0xFF,	19,	20	},
		{ X1205_REG_Y2K0,	0xFF,	19,	20	},
	};

	/* check that registers have bits a 0 where expected */
	for (i = 0; i < ARRAY_SIZE(probe_zero_pattern); i += 2) {
		unsigned char buf;

		unsigned char addr[2] = { 0, probe_zero_pattern[i] };

		struct i2c_msg msgs[2] = {
			{ client->addr, 0, 2, addr },
			{ client->addr, I2C_M_RD, 1, &buf },
		};

		if ((xfer = i2c_transfer(client->adapter, msgs, 2)) != 2) {
			dev_err(&client->dev,
				"%s: could not read register %x\n",
				__FUNCTION__, probe_zero_pattern[i]);

			return -EIO;
		}

		if ((buf & probe_zero_pattern[i+1]) != 0) {
			dev_err(&client->dev,
				"%s: register=%02x, zero pattern=%d, value=%x\n",
				__FUNCTION__, probe_zero_pattern[i], i, buf);

			return -ENODEV;
		}
	}

	/* check limits (only registers with bcd values) */
	for (i = 0; i < ARRAY_SIZE(probe_limits_pattern); i++) {
		unsigned char reg, value;

		unsigned char addr[2] = { 0, probe_limits_pattern[i].reg };

		struct i2c_msg msgs[2] = {
			{ client->addr, 0, 2, addr },
			{ client->addr, I2C_M_RD, 1, &reg },
		};

		if ((xfer = i2c_transfer(client->adapter, msgs, 2)) != 2) {
			dev_err(&client->dev,
				"%s: could not read register %x\n",
				__FUNCTION__, probe_limits_pattern[i].reg);

			return -EIO;
		}

		value = BCD2BIN(reg & probe_limits_pattern[i].mask);

		if (value > probe_limits_pattern[i].max ||
			value < probe_limits_pattern[i].min) {
			dev_dbg(&client->dev,
				"%s: register=%x, lim pattern=%d, value=%d\n",
				__FUNCTION__, probe_limits_pattern[i].reg,
				i, value);

			return -ENODEV;
		}
	}

	return 0;
}

static int x1205_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
	return x1205_get_datetime(to_i2c_client(dev),
		&alrm->time, X1205_ALM0_BASE);
}

static int x1205_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
	return x1205_set_datetime(to_i2c_client(dev),
		&alrm->time, 1, X1205_ALM0_BASE);
}

static int x1205_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
	return x1205_get_datetime(to_i2c_client(dev),
		tm, X1205_CCR_BASE);
}

static int x1205_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
	return x1205_set_datetime(to_i2c_client(dev),
		tm, 1, X1205_CCR_BASE);
}

static int x1205_rtc_proc(struct device *dev, struct seq_file *seq)
{
	int err, dtrim, atrim;

	if ((err = x1205_get_dtrim(to_i2c_client(dev), &dtrim)) == 0)
		seq_printf(seq, "digital_trim\t: %d ppm\n", dtrim);

	if ((err = x1205_get_atrim(to_i2c_client(dev), &atrim)) == 0)
		seq_printf(seq, "analog_trim\t: %d.%02d pF\n",
			atrim / 1000, atrim % 1000);
	return 0;
}

static const struct rtc_class_ops x1205_rtc_ops = {
	.proc		= x1205_rtc_proc,
	.read_time	= x1205_rtc_read_time,
	.set_time	= x1205_rtc_set_time,
	.read_alarm	= x1205_rtc_read_alarm,
	.set_alarm	= x1205_rtc_set_alarm,
};

static ssize_t x1205_sysfs_show_atrim(struct device *dev,
				struct device_attribute *attr, char *buf)
{
	int err, atrim;

	err = x1205_get_atrim(to_i2c_client(dev), &atrim);
	if (err)
		return err;

	return sprintf(buf, "%d.%02d pF\n", atrim / 1000, atrim % 1000);
}
static DEVICE_ATTR(atrim, S_IRUGO, x1205_sysfs_show_atrim, NULL);

static ssize_t x1205_sysfs_show_dtrim(struct device *dev,
				struct device_attribute *attr, char *buf)
{
	int err, dtrim;

	err = x1205_get_dtrim(to_i2c_client(dev), &dtrim);
	if (err)
		return err;

	return sprintf(buf, "%d ppm\n", dtrim);
}
static DEVICE_ATTR(dtrim, S_IRUGO, x1205_sysfs_show_dtrim, NULL);

static int x1205_attach(struct i2c_adapter *adapter)
{
	return i2c_probe(adapter, &addr_data, x1205_probe);
}

static int x1205_probe(struct i2c_adapter *adapter, int address, int kind)
{
	int err = 0;
	unsigned char sr;
	struct i2c_client *client;
	struct rtc_device *rtc;

	dev_dbg(&adapter->dev, "%s\n", __FUNCTION__);

	if (!i2c_check_functionality(adapter, I2C_FUNC_I2C)) {
		err = -ENODEV;
		goto exit;
	}

	if (!(client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL))) {
		err = -ENOMEM;
		goto exit;
	}

	/* I2C client */
	client->addr = address;
	client->driver = &x1205_driver;
	client->adapter	= adapter;

	strlcpy(client->name, x1205_driver.driver.name, I2C_NAME_SIZE);

	/* Verify the chip is really an X1205 */
	if (kind < 0) {
		if (x1205_validate_client(client) < 0) {
			err = -ENODEV;
			goto exit_kfree;
		}
	}

	/* Inform the i2c layer */
	if ((err = i2c_attach_client(client)))
		goto exit_kfree;

	dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");

	rtc = rtc_device_register(x1205_driver.driver.name, &client->dev,
				&x1205_rtc_ops, THIS_MODULE);

	if (IS_ERR(rtc)) {
		err = PTR_ERR(rtc);
		goto exit_detach;
	}

	i2c_set_clientdata(client, rtc);

	/* Check for power failures and eventualy enable the osc */
	if ((err = x1205_get_status(client, &sr)) == 0) {
		if (sr & X1205_SR_RTCF) {
			dev_err(&client->dev,
				"power failure detected, "
				"please set the clock\n");
			udelay(50);
			x1205_fix_osc(client);
		}
	}
	else
		dev_err(&client->dev, "couldn't read status\n");

	err = device_create_file(&client->dev, &dev_attr_atrim);
	if (err) goto exit_devreg;
	err = device_create_file(&client->dev, &dev_attr_dtrim);
	if (err) goto exit_atrim;

	return 0;

exit_atrim:
	device_remove_file(&client->dev, &dev_attr_atrim);

exit_devreg:
	rtc_device_unregister(rtc);

exit_detach:
	i2c_detach_client(client);

exit_kfree:
	kfree(client);

exit:
	return err;
}

static int x1205_detach(struct i2c_client *client)
{
	int err;
	struct rtc_device *rtc = i2c_get_clientdata(client);

 	if (rtc)
		rtc_device_unregister(rtc);

	if ((err = i2c_detach_client(client)))
		return err;

	kfree(client);

	return 0;
}

static int __init x1205_init(void)
{
	return i2c_add_driver(&x1205_driver);
}

static void __exit x1205_exit(void)
{
	i2c_del_driver(&x1205_driver);
}

MODULE_AUTHOR(
	"Karen Spearel <kas111 at gmail dot com>, "
	"Alessandro Zummo <[e-mail]>");
MODULE_DESCRIPTION("Xicor/Intersil X1205 RTC driver");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_VERSION);

module_init(x1205_init);
module_exit(x1205_exit);