// SPDX-License-Identifier: GPL-2.0-only
/*
 * Windfarm PowerMac thermal control. AD7417 sensors
 *
 * Copyright 2012 Benjamin Herrenschmidt, IBM Corp.
 */

#include <linux/types.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/wait.h>
#include <linux/i2c.h>

#include <asm/machdep.h>
#include <asm/io.h>
#include <asm/sections.h>

#include "windfarm.h"
#include "windfarm_mpu.h"

#define VERSION "1.0"

struct wf_ad7417_priv {
        struct kref             ref;
        struct i2c_client       *i2c;
        u8                      config;
        u8                      cpu;
        const struct mpu_data   *mpu;
        struct wf_sensor        sensors[5];
        struct mutex            lock;
};

static int wf_ad7417_temp_get(struct wf_sensor *sr, s32 *value)
{
        struct wf_ad7417_priv *pv = sr->priv;
        u8 buf[2];
        s16 raw;
        int rc;

        *value = 0;
        mutex_lock(&pv->lock);

        /* Read temp register */
        buf[0] = 0;
        rc = i2c_master_send(pv->i2c, buf, 1);
        if (rc < 0)
                goto error;
        rc = i2c_master_recv(pv->i2c, buf, 2);
        if (rc < 0)
                goto error;

        /* Read a a 16-bit signed value */
        raw = be16_to_cpup((__le16 *)buf);

        /* Convert 8.8-bit to 16.16 fixed point */
        *value = ((s32)raw) << 8;

        mutex_unlock(&pv->lock);
        return 0;

error:
        mutex_unlock(&pv->lock);
        return -1;
}

/*
 * Scaling factors for the AD7417 ADC converters (except
 * for the CPU diode which is obtained from the EEPROM).
 * Those values are obtained from the property list of
 * the darwin driver
 */
#define ADC_12V_CURRENT_SCALE   0x0320  /* _AD2 */
#define ADC_CPU_VOLTAGE_SCALE   0x00a0  /* _AD3 */
#define ADC_CPU_CURRENT_SCALE   0x1f40  /* _AD4 */

static void wf_ad7417_adc_convert(struct wf_ad7417_priv *pv,
                                  int chan, s32 raw, s32 *value)
{
        switch(chan) {
        case 1: /* Diode */
                *value = (raw * (s32)pv->mpu->mdiode +
                        ((s32)pv->mpu->bdiode << 12)) >> 2;
                break;
        case 2: /* 12v current */
                *value = raw * ADC_12V_CURRENT_SCALE;
                break;
        case 3: /* core voltage */
                *value = raw * ADC_CPU_VOLTAGE_SCALE;
                break;
        case 4: /* core current */
                *value = raw * ADC_CPU_CURRENT_SCALE;
                break;
        }
}

static int wf_ad7417_adc_get(struct wf_sensor *sr, s32 *value)
{
        struct wf_ad7417_priv *pv = sr->priv;
        int chan = sr - pv->sensors;
        int i, rc;
        u8 buf[2];
        u16 raw;

        *value = 0;
        mutex_lock(&pv->lock);
        for (i = 0; i < 10; i++) {
                /* Set channel */
                buf[0] = 1;
                buf[1] = (pv->config & 0x1f) | (chan << 5);
                rc = i2c_master_send(pv->i2c, buf, 2);
                if (rc < 0)
                        goto error;

                /* Wait for conversion */
                msleep(1);

                /* Switch to data register */
                buf[0] = 4;
                rc = i2c_master_send(pv->i2c, buf, 1);
                if (rc < 0)
                        goto error;

                /* Read result */
                rc = i2c_master_recv(pv->i2c, buf, 2);
                if (rc < 0)
                        goto error;

                /* Read a a 16-bit signed value */
                raw = be16_to_cpup((__le16 *)buf) >> 6;
                wf_ad7417_adc_convert(pv, chan, raw, value);

                dev_vdbg(&pv->i2c->dev, "ADC chan %d [%s]"
                         " raw value: 0x%x, conv to: 0x%08x\n",
                         chan, sr->name, raw, *value);

                mutex_unlock(&pv->lock);
                return 0;

        error:
                dev_dbg(&pv->i2c->dev,
                          "Error reading ADC, try %d...\n", i);
                if (i < 9)
                        msleep(10);
        }
        mutex_unlock(&pv->lock);
        return -1;
}

static void wf_ad7417_release(struct kref *ref)
{
        struct wf_ad7417_priv *pv = container_of(ref,
                                                 struct wf_ad7417_priv, ref);
        kfree(pv);
}

static void wf_ad7417_sensor_release(struct wf_sensor *sr)
{
        struct wf_ad7417_priv *pv = sr->priv;

        kfree(sr->name);
        kref_put(&pv->ref, wf_ad7417_release);
}

static const struct wf_sensor_ops wf_ad7417_temp_ops = {
        .get_value      = wf_ad7417_temp_get,
        .release        = wf_ad7417_sensor_release,
        .owner          = THIS_MODULE,
};

static const struct wf_sensor_ops wf_ad7417_adc_ops = {
        .get_value      = wf_ad7417_adc_get,
        .release        = wf_ad7417_sensor_release,
        .owner          = THIS_MODULE,
};

static void wf_ad7417_add_sensor(struct wf_ad7417_priv *pv,
                                 int index, const char *name,
                                 const struct wf_sensor_ops *ops)
{
        pv->sensors[index].name = kasprintf(GFP_KERNEL, "%s-%d", name, pv->cpu);
        pv->sensors[index].priv = pv;
        pv->sensors[index].ops = ops;
        if (!wf_register_sensor(&pv->sensors[index]))
                kref_get(&pv->ref);
}

static void wf_ad7417_init_chip(struct wf_ad7417_priv *pv)
{
        int rc;
        u8 buf[2];
        u8 config = 0;

        /*
         * Read ADC the configuration register and cache it. We
         * also make sure Config2 contains proper values, I've seen
         * cases where we got stale grabage in there, thus preventing
         * proper reading of conv. values
         */

        /* Clear Config2 */
        buf[0] = 5;
        buf[1] = 0;
        i2c_master_send(pv->i2c, buf, 2);

        /* Read & cache Config1 */
        buf[0] = 1;
        rc = i2c_master_send(pv->i2c, buf, 1);
        if (rc > 0) {
                rc = i2c_master_recv(pv->i2c, buf, 1);
                if (rc > 0) {
                        config = buf[0];

                        dev_dbg(&pv->i2c->dev, "ADC config reg: %02x\n",
                                config);

                        /* Disable shutdown mode */
                        config &= 0xfe;
                        buf[0] = 1;
                        buf[1] = config;
                        rc = i2c_master_send(pv->i2c, buf, 2);
                }
        }
        if (rc <= 0)
                dev_err(&pv->i2c->dev, "Error reading ADC config\n");

        pv->config = config;
}

static int wf_ad7417_probe(struct i2c_client *client)
{
        struct wf_ad7417_priv *pv;
        const struct mpu_data *mpu;
        const char *loc;
        int cpu_nr;

        loc = of_get_property(client->dev.of_node, "hwsensor-location", NULL);
        if (!loc) {
                dev_warn(&client->dev, "Missing hwsensor-location property!\n");
                return -ENXIO;
        }

        /*
         * Identify which CPU we belong to by looking at the first entry
         * in the hwsensor-location list
         */
        if (!strncmp(loc, "CPU A", 5))
                cpu_nr = 0;
        else if (!strncmp(loc, "CPU B", 5))
                cpu_nr = 1;
        else {
                pr_err("wf_ad7417: Can't identify location %s\n", loc);
                return -ENXIO;
        }
        mpu = wf_get_mpu(cpu_nr);
        if (!mpu) {
                dev_err(&client->dev, "Failed to retrieve MPU data\n");
                return -ENXIO;
        }

        pv = kzalloc_obj(struct wf_ad7417_priv);
        if (pv == NULL)
                return -ENODEV;

        kref_init(&pv->ref);
        mutex_init(&pv->lock);
        pv->i2c = client;
        pv->cpu = cpu_nr;
        pv->mpu = mpu;
        dev_set_drvdata(&client->dev, pv);

        /* Initialize the chip */
        wf_ad7417_init_chip(pv);

        /*
         * We cannot rely on Apple device-tree giving us child
         * node with the names of the individual sensors so we
         * just hard code what we know about them
         */
        wf_ad7417_add_sensor(pv, 0, "cpu-amb-temp", &wf_ad7417_temp_ops);
        wf_ad7417_add_sensor(pv, 1, "cpu-diode-temp", &wf_ad7417_adc_ops);
        wf_ad7417_add_sensor(pv, 2, "cpu-12v-current", &wf_ad7417_adc_ops);
        wf_ad7417_add_sensor(pv, 3, "cpu-voltage", &wf_ad7417_adc_ops);
        wf_ad7417_add_sensor(pv, 4, "cpu-current", &wf_ad7417_adc_ops);

        return 0;
}

static void wf_ad7417_remove(struct i2c_client *client)
{
        struct wf_ad7417_priv *pv = dev_get_drvdata(&client->dev);
        int i;

        /* Mark client detached */
        pv->i2c = NULL;

        /* Release sensor */
        for (i = 0; i < 5; i++)
                wf_unregister_sensor(&pv->sensors[i]);

        kref_put(&pv->ref, wf_ad7417_release);
}

static const struct i2c_device_id wf_ad7417_id[] = {
        { "MAC,ad7417" },
        { }
};
MODULE_DEVICE_TABLE(i2c, wf_ad7417_id);

static const struct of_device_id wf_ad7417_of_id[] = {
        { .compatible = "ad7417", },
        { }
};
MODULE_DEVICE_TABLE(of, wf_ad7417_of_id);

static struct i2c_driver wf_ad7417_driver = {
        .driver = {
                .name   = "wf_ad7417",
                .of_match_table = wf_ad7417_of_id,
        },
        .probe          = wf_ad7417_probe,
        .remove         = wf_ad7417_remove,
        .id_table       = wf_ad7417_id,
};

static int wf_ad7417_init(void)
{
        /* This is only supported on these machines */
        if (!of_machine_is_compatible("PowerMac7,2") &&
            !of_machine_is_compatible("PowerMac7,3") &&
            !of_machine_is_compatible("RackMac3,1"))
                return -ENODEV;

        return i2c_add_driver(&wf_ad7417_driver);
}

static void wf_ad7417_exit(void)
{
        i2c_del_driver(&wf_ad7417_driver);
}

module_init(wf_ad7417_init);
module_exit(wf_ad7417_exit);

MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
MODULE_DESCRIPTION("ad7417 sensor driver for PowerMacs");
MODULE_LICENSE("GPL");