hwmon: add max1111 Low-power Multichannel Serial 8-bit ADCs

Driver based on corgi_ssp.c and sharpsl_pm.c, previously done by Richard
Purdie and many others.

Now changed to generic HWMON device and expose all the ADC input value
through sysfs.

Signed-off-by: Eric Miao <eric.miao@marvell.com>
Acked-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 231 insertions, 0 deletions

diff --git a/drivers/hwmon/max1111.c b/drivers/hwmon/max1111.c
new file mode 100644
index 000000000000..12c05774a1c3
--- /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");