diff options
Diffstat (limited to 'drivers/hwmon/max1111.c')
| -rw-r--r-- | drivers/hwmon/max1111.c | 231 |
1 files changed, 231 insertions, 0 deletions
diff --git a/drivers/hwmon/max1111.c b/drivers/hwmon/max1111.c new file mode 100644 index 00000000000..12c05774a1c --- /dev/null +++ b/drivers/hwmon/max1111.c @@ -0,0 +1,231 @@ +/* + * max1111.c - +2.7V, Low-Power, Multichannel, Serial 8-bit ADCs + * + * Based on arch/arm/mach-pxa/corgi_ssp.c + * + * Copyright (C) 2004-2005 Richard Purdie + * + * Copyright (C) 2008 Marvell International Ltd. + * Eric Miao <eric.miao@marvell.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * publishhed by the Free Software Foundation. + */ + +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/err.h> +#include <linux/hwmon.h> +#include <linux/hwmon-sysfs.h> +#include <linux/spi/spi.h> + +#define MAX1111_TX_BUF_SIZE 1 +#define MAX1111_RX_BUF_SIZE 2 + +/* MAX1111 Commands */ +#define MAX1111_CTRL_PD0 (1u << 0) +#define MAX1111_CTRL_PD1 (1u << 1) +#define MAX1111_CTRL_SGL (1u << 2) +#define MAX1111_CTRL_UNI (1u << 3) +#define MAX1111_CTRL_SEL_SH (5) /* NOTE: bit 4 is ignored */ +#define MAX1111_CTRL_STR (1u << 7) + +struct max1111_data { + struct spi_device *spi; + struct device *hwmon_dev; + struct spi_message msg; + struct spi_transfer xfer[2]; + uint8_t *tx_buf; + uint8_t *rx_buf; +}; + +static int max1111_read(struct device *dev, int channel) +{ + struct max1111_data *data = dev_get_drvdata(dev); + uint8_t v1, v2; + int err; + + data->tx_buf[0] = (channel << MAX1111_CTRL_SEL_SH) | + MAX1111_CTRL_PD0 | MAX1111_CTRL_PD1 | + MAX1111_CTRL_SGL | MAX1111_CTRL_UNI | MAX1111_CTRL_STR; + + err = spi_sync(data->spi, &data->msg); + if (err < 0) { + dev_err(dev, "spi_sync failed with %d\n", err); + return err; + } + + v1 = data->rx_buf[0]; + v2 = data->rx_buf[1]; + + if ((v1 & 0xc0) || (v2 & 0x3f)) + return -EINVAL; + + return (v1 << 2) | (v2 >> 6); +} + +/* + * NOTE: SPI devices do not have a default 'name' attribute, which is + * likely to be used by hwmon applications to distinguish between + * different devices, explicitly add a name attribute here. + */ +static ssize_t show_name(struct device *dev, + struct device_attribute *attr, char *buf) +{ + return sprintf(buf, "max1111\n"); +} + +static ssize_t show_adc(struct device *dev, + struct device_attribute *attr, char *buf) +{ + int channel = to_sensor_dev_attr(attr)->index; + int ret; + + ret = max1111_read(dev, channel); + if (ret < 0) + return ret; + + return sprintf(buf, "%d\n", ret); +} + +#define MAX1111_ADC_ATTR(_id) \ + SENSOR_DEVICE_ATTR(adc##_id##_in, S_IRUGO, show_adc, NULL, _id) + +static DEVICE_ATTR(name, S_IRUGO, show_name, NULL); +static MAX1111_ADC_ATTR(0); +static MAX1111_ADC_ATTR(1); +static MAX1111_ADC_ATTR(2); +static MAX1111_ADC_ATTR(3); + +static struct attribute *max1111_attributes[] = { + &dev_attr_name.attr, + &sensor_dev_attr_adc0_in.dev_attr.attr, + &sensor_dev_attr_adc1_in.dev_attr.attr, + &sensor_dev_attr_adc2_in.dev_attr.attr, + &sensor_dev_attr_adc3_in.dev_attr.attr, + NULL, +}; + +static const struct attribute_group max1111_attr_group = { + .attrs = max1111_attributes, +}; + +static int setup_transfer(struct max1111_data *data) +{ + struct spi_message *m; + struct spi_transfer *x; + + data->tx_buf = kmalloc(MAX1111_TX_BUF_SIZE, GFP_KERNEL); + if (!data->tx_buf) + return -ENOMEM; + + data->rx_buf = kmalloc(MAX1111_RX_BUF_SIZE, GFP_KERNEL); + if (!data->rx_buf) { + kfree(data->tx_buf); + return -ENOMEM; + } + + m = &data->msg; + x = &data->xfer[0]; + + spi_message_init(m); + + x->tx_buf = &data->tx_buf[0]; + x->len = 1; + spi_message_add_tail(x, m); + + x++; + x->rx_buf = &data->rx_buf[0]; + x->len = 2; + spi_message_add_tail(x, m); + + return 0; +} + +static int __devinit max1111_probe(struct spi_device *spi) +{ + struct max1111_data *data; + int err; + + spi->bits_per_word = 8; + spi->mode = SPI_MODE_0; + err = spi_setup(spi); + if (err < 0) + return err; + + data = kzalloc(sizeof(struct max1111_data), GFP_KERNEL); + if (data == NULL) { + dev_err(&spi->dev, "failed to allocate memory\n"); + return -ENOMEM; + } + + err = setup_transfer(data); + if (err) + goto err_free_data; + + data->spi = spi; + spi_set_drvdata(spi, data); + + err = sysfs_create_group(&spi->dev.kobj, &max1111_attr_group); + if (err) { + dev_err(&spi->dev, "failed to create attribute group\n"); + goto err_free_all; + } + + data->hwmon_dev = hwmon_device_register(&spi->dev); + if (IS_ERR(data->hwmon_dev)) { + dev_err(&spi->dev, "failed to create hwmon device\n"); + err = PTR_ERR(data->hwmon_dev); + goto err_remove; + } + + return 0; + +err_remove: + sysfs_remove_group(&spi->dev.kobj, &max1111_attr_group); +err_free_all: + kfree(data->rx_buf); + kfree(data->tx_buf); +err_free_data: + kfree(data); + return err; +} + +static int __devexit max1111_remove(struct spi_device *spi) +{ + struct max1111_data *data = spi_get_drvdata(spi); + + hwmon_device_unregister(data->hwmon_dev); + sysfs_remove_group(&spi->dev.kobj, &max1111_attr_group); + kfree(data->rx_buf); + kfree(data->tx_buf); + kfree(data); + return 0; +} + +static struct spi_driver max1111_driver = { + .driver = { + .name = "max1111", + .owner = THIS_MODULE, + }, + .probe = max1111_probe, + .remove = __devexit_p(max1111_remove), +}; + +static int __init max1111_init(void) +{ + return spi_register_driver(&max1111_driver); +} +module_init(max1111_init); + +static void __exit max1111_exit(void) +{ + spi_unregister_driver(&max1111_driver); +} +module_exit(max1111_exit); + +MODULE_AUTHOR("Eric Miao <eric.miao@marvell.com>"); +MODULE_DESCRIPTION("MAX1111 ADC Driver"); +MODULE_LICENSE("GPL"); |