// SPDX-License-Identifier: GPL-2.0-only
/*
 * Windfarm PowerMac thermal control. FCU fan control
 *
 * Copyright 2012 Benjamin Herrenschmidt, IBM Corp.
 */
#undef DEBUG

#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"

#ifdef DEBUG
#define DBG(args...)    printk(args)
#else
#define DBG(args...)    do { } while(0)
#endif

/*
 * This option is "weird" :) Basically, if you define this to 1
 * the control loop for the RPMs fans (not PWMs) will apply the
 * correction factor obtained from the PID to the actual RPM
 * speed read from the FCU.
 *
 * If you define the below constant to 0, then it will be
 * applied to the setpoint RPM speed, that is basically the
 * speed we proviously "asked" for.
 *
 * I'm using 0 for now which is what therm_pm72 used to do and
 * what Darwin -apparently- does based on observed behaviour.
 */
#define RPM_PID_USE_ACTUAL_SPEED        0

/* Default min/max for pumps */
#define CPU_PUMP_OUTPUT_MAX             3200
#define CPU_PUMP_OUTPUT_MIN             1250

#define FCU_FAN_RPM             0
#define FCU_FAN_PWM             1

struct wf_fcu_priv {
        struct kref             ref;
        struct i2c_client       *i2c;
        struct mutex            lock;
        struct list_head        fan_list;
        int                     rpm_shift;
};

struct wf_fcu_fan {
        struct list_head        link;
        int                     id;
        s32                     min, max, target;
        struct wf_fcu_priv      *fcu_priv;
        struct wf_control       ctrl;
};

static void wf_fcu_release(struct kref *ref)
{
        struct wf_fcu_priv *pv = container_of(ref, struct wf_fcu_priv, ref);

        kfree(pv);
}

static void wf_fcu_fan_release(struct wf_control *ct)
{
        struct wf_fcu_fan *fan = ct->priv;

        kref_put(&fan->fcu_priv->ref, wf_fcu_release);
        kfree(fan);
}

static int wf_fcu_read_reg(struct wf_fcu_priv *pv, int reg,
                           unsigned char *buf, int nb)
{
        int tries, nr, nw;

        mutex_lock(&pv->lock);

        buf[0] = reg;
        tries = 0;
        for (;;) {
                nw = i2c_master_send(pv->i2c, buf, 1);
                if (nw > 0 || (nw < 0 && nw != -EIO) || tries >= 100)
                        break;
                msleep(10);
                ++tries;
        }
        if (nw <= 0) {
                pr_err("Failure writing address to FCU: %d", nw);
                nr = nw;
                goto bail;
        }
        tries = 0;
        for (;;) {
                nr = i2c_master_recv(pv->i2c, buf, nb);
                if (nr > 0 || (nr < 0 && nr != -ENODEV) || tries >= 100)
                        break;
                msleep(10);
                ++tries;
        }
        if (nr <= 0)
                pr_err("wf_fcu: Failure reading data from FCU: %d", nw);
 bail:
        mutex_unlock(&pv->lock);
        return nr;
}

static int wf_fcu_write_reg(struct wf_fcu_priv *pv, int reg,
                            const unsigned char *ptr, int nb)
{
        int tries, nw;
        unsigned char buf[16];

        buf[0] = reg;
        memcpy(buf+1, ptr, nb);
        ++nb;
        tries = 0;
        for (;;) {
                nw = i2c_master_send(pv->i2c, buf, nb);
                if (nw > 0 || (nw < 0 && nw != -EIO) || tries >= 100)
                        break;
                msleep(10);
                ++tries;
        }
        if (nw < 0)
                pr_err("wf_fcu: Failure writing to FCU: %d", nw);
        return nw;
}

static int wf_fcu_fan_set_rpm(struct wf_control *ct, s32 value)
{
        struct wf_fcu_fan *fan = ct->priv;
        struct wf_fcu_priv *pv = fan->fcu_priv;
        int rc, shift = pv->rpm_shift;
        unsigned char buf[2];

        if (value < fan->min)
                value = fan->min;
        if (value > fan->max)
                value = fan->max;

        fan->target = value;

        buf[0] = value >> (8 - shift);
        buf[1] = value << shift;
        rc = wf_fcu_write_reg(pv, 0x10 + (fan->id * 2), buf, 2);
        if (rc < 0)
                return -EIO;
        return 0;
}

static int wf_fcu_fan_get_rpm(struct wf_control *ct, s32 *value)
{
        struct wf_fcu_fan *fan = ct->priv;
        struct wf_fcu_priv *pv = fan->fcu_priv;
        int rc, reg_base, shift = pv->rpm_shift;
        unsigned char failure;
        unsigned char active;
        unsigned char buf[2];

        rc = wf_fcu_read_reg(pv, 0xb, &failure, 1);
        if (rc != 1)
                return -EIO;
        if ((failure & (1 << fan->id)) != 0)
                return -EFAULT;
        rc = wf_fcu_read_reg(pv, 0xd, &active, 1);
        if (rc != 1)
                return -EIO;
        if ((active & (1 << fan->id)) == 0)
                return -ENXIO;

        /* Programmed value or real current speed */
#if RPM_PID_USE_ACTUAL_SPEED
        reg_base = 0x11;
#else
        reg_base = 0x10;
#endif
        rc = wf_fcu_read_reg(pv, reg_base + (fan->id * 2), buf, 2);
        if (rc != 2)
                return -EIO;

        *value = (buf[0] << (8 - shift)) | buf[1] >> shift;

        return 0;
}

static int wf_fcu_fan_set_pwm(struct wf_control *ct, s32 value)
{
        struct wf_fcu_fan *fan = ct->priv;
        struct wf_fcu_priv *pv = fan->fcu_priv;
        unsigned char buf[2];
        int rc;

        if (value < fan->min)
                value = fan->min;
        if (value > fan->max)
                value = fan->max;

        fan->target = value;

        value = (value * 2559) / 1000;
        buf[0] = value;
        rc = wf_fcu_write_reg(pv, 0x30 + (fan->id * 2), buf, 1);
        if (rc < 0)
                return -EIO;
        return 0;
}

static int wf_fcu_fan_get_pwm(struct wf_control *ct, s32 *value)
{
        struct wf_fcu_fan *fan = ct->priv;
        struct wf_fcu_priv *pv = fan->fcu_priv;
        unsigned char failure;
        unsigned char active;
        unsigned char buf[2];
        int rc;

        rc = wf_fcu_read_reg(pv, 0x2b, &failure, 1);
        if (rc != 1)
                return -EIO;
        if ((failure & (1 << fan->id)) != 0)
                return -EFAULT;
        rc = wf_fcu_read_reg(pv, 0x2d, &active, 1);
        if (rc != 1)
                return -EIO;
        if ((active & (1 << fan->id)) == 0)
                return -ENXIO;

        rc = wf_fcu_read_reg(pv, 0x30 + (fan->id * 2), buf, 1);
        if (rc != 1)
                return -EIO;

        *value = (((s32)buf[0]) * 1000) / 2559;

        return 0;
}

static s32 wf_fcu_fan_min(struct wf_control *ct)
{
        struct wf_fcu_fan *fan = ct->priv;

        return fan->min;
}

static s32 wf_fcu_fan_max(struct wf_control *ct)
{
        struct wf_fcu_fan *fan = ct->priv;

        return fan->max;
}

static const struct wf_control_ops wf_fcu_fan_rpm_ops = {
        .set_value      = wf_fcu_fan_set_rpm,
        .get_value      = wf_fcu_fan_get_rpm,
        .get_min        = wf_fcu_fan_min,
        .get_max        = wf_fcu_fan_max,
        .release        = wf_fcu_fan_release,
        .owner          = THIS_MODULE,
};

static const struct wf_control_ops wf_fcu_fan_pwm_ops = {
        .set_value      = wf_fcu_fan_set_pwm,
        .get_value      = wf_fcu_fan_get_pwm,
        .get_min        = wf_fcu_fan_min,
        .get_max        = wf_fcu_fan_max,
        .release        = wf_fcu_fan_release,
        .owner          = THIS_MODULE,
};

static void wf_fcu_get_pump_minmax(struct wf_fcu_fan *fan)
{
        const struct mpu_data *mpu = wf_get_mpu(0);
        u16 pump_min = 0, pump_max = 0xffff;
        u16 tmp[4];

        /* Try to fetch pumps min/max infos from eeprom */
        if (mpu) {
                memcpy(&tmp, mpu->processor_part_num, 8);
                if (tmp[0] != 0xffff && tmp[1] != 0xffff) {
                        pump_min = max(pump_min, tmp[0]);
                        pump_max = min(pump_max, tmp[1]);
                }
                if (tmp[2] != 0xffff && tmp[3] != 0xffff) {
                        pump_min = max(pump_min, tmp[2]);
                        pump_max = min(pump_max, tmp[3]);
                }
        }

        /* Double check the values, this _IS_ needed as the EEPROM on
         * some dual 2.5Ghz G5s seem, at least, to have both min & max
         * same to the same value ... (grrrr)
         */
        if (pump_min == pump_max || pump_min == 0 || pump_max == 0xffff) {
                pump_min = CPU_PUMP_OUTPUT_MIN;
                pump_max = CPU_PUMP_OUTPUT_MAX;
        }

        fan->min = pump_min;
        fan->max = pump_max;

        DBG("wf_fcu: pump min/max for %s set to: [%d..%d] RPM\n",
            fan->ctrl.name, pump_min, pump_max);
}

static void wf_fcu_get_rpmfan_minmax(struct wf_fcu_fan *fan)
{
        struct wf_fcu_priv *pv = fan->fcu_priv;
        const struct mpu_data *mpu0 = wf_get_mpu(0);
        const struct mpu_data *mpu1 = wf_get_mpu(1);

        /* Default */
        fan->min = 2400 >> pv->rpm_shift;
        fan->max = 56000 >> pv->rpm_shift;

        /* CPU fans have min/max in MPU */
        if (mpu0 && !strcmp(fan->ctrl.name, "cpu-front-fan-0")) {
                fan->min = max(fan->min, (s32)mpu0->rminn_intake_fan);
                fan->max = min(fan->max, (s32)mpu0->rmaxn_intake_fan);
                goto bail;
        }
        if (mpu1 && !strcmp(fan->ctrl.name, "cpu-front-fan-1")) {
                fan->min = max(fan->min, (s32)mpu1->rminn_intake_fan);
                fan->max = min(fan->max, (s32)mpu1->rmaxn_intake_fan);
                goto bail;
        }
        if (mpu0 && !strcmp(fan->ctrl.name, "cpu-rear-fan-0")) {
                fan->min = max(fan->min, (s32)mpu0->rminn_exhaust_fan);
                fan->max = min(fan->max, (s32)mpu0->rmaxn_exhaust_fan);
                goto bail;
        }
        if (mpu1 && !strcmp(fan->ctrl.name, "cpu-rear-fan-1")) {
                fan->min = max(fan->min, (s32)mpu1->rminn_exhaust_fan);
                fan->max = min(fan->max, (s32)mpu1->rmaxn_exhaust_fan);
                goto bail;
        }
        /* Rackmac variants, we just use mpu0 intake */
        if (!strncmp(fan->ctrl.name, "cpu-fan", 7)) {
                fan->min = max(fan->min, (s32)mpu0->rminn_intake_fan);
                fan->max = min(fan->max, (s32)mpu0->rmaxn_intake_fan);
                goto bail;
        }
 bail:
        DBG("wf_fcu: fan min/max for %s set to: [%d..%d] RPM\n",
            fan->ctrl.name, fan->min, fan->max);
}

static void wf_fcu_add_fan(struct wf_fcu_priv *pv, const char *name,
                           int type, int id)
{
        struct wf_fcu_fan *fan;

        fan = kzalloc_obj(*fan);
        if (!fan)
                return;
        fan->fcu_priv = pv;
        fan->id = id;
        fan->ctrl.name = name;
        fan->ctrl.priv = fan;

        /* min/max is oddball but the code comes from
         * therm_pm72 which seems to work so ...
         */
        if (type == FCU_FAN_RPM) {
                if (!strncmp(name, "cpu-pump", strlen("cpu-pump")))
                        wf_fcu_get_pump_minmax(fan);
                else
                        wf_fcu_get_rpmfan_minmax(fan);
                fan->ctrl.type = WF_CONTROL_RPM_FAN;
                fan->ctrl.ops = &wf_fcu_fan_rpm_ops;
        } else {
                fan->min = 10;
                fan->max = 100;
                fan->ctrl.type = WF_CONTROL_PWM_FAN;
                fan->ctrl.ops = &wf_fcu_fan_pwm_ops;
        }

        if (wf_register_control(&fan->ctrl)) {
                pr_err("wf_fcu: Failed to register fan %s\n", name);
                kfree(fan);
                return;
        }
        list_add(&fan->link, &pv->fan_list);
        kref_get(&pv->ref);
}

static void wf_fcu_lookup_fans(struct wf_fcu_priv *pv)
{
        /* Translation of device-tree location properties to
         * windfarm fan names
         */
        static const struct {
                const char *dt_name;    /* Device-tree name */
                const char *ct_name;    /* Control name */
        } loc_trans[] = {
                { "BACKSIDE",           "backside-fan",         },
                { "SYS CTRLR FAN",      "backside-fan",         },
                { "DRIVE BAY",          "drive-bay-fan",        },
                { "SLOT",               "slots-fan",            },
                { "PCI FAN",            "slots-fan",            },
                { "CPU A INTAKE",       "cpu-front-fan-0",      },
                { "CPU A EXHAUST",      "cpu-rear-fan-0",       },
                { "CPU B INTAKE",       "cpu-front-fan-1",      },
                { "CPU B EXHAUST",      "cpu-rear-fan-1",       },
                { "CPU A PUMP",         "cpu-pump-0",           },
                { "CPU B PUMP",         "cpu-pump-1",           },
                { "CPU A 1",            "cpu-fan-a-0",          },
                { "CPU A 2",            "cpu-fan-b-0",          },
                { "CPU A 3",            "cpu-fan-c-0",          },
                { "CPU B 1",            "cpu-fan-a-1",          },
                { "CPU B 2",            "cpu-fan-b-1",          },
                { "CPU B 3",            "cpu-fan-c-1",          },
        };
        struct device_node *np, *fcu = pv->i2c->dev.of_node;
        int i;

        DBG("Looking up FCU controls in device-tree...\n");

        for_each_child_of_node(fcu, np) {
                int id, type = -1;
                const char *loc;
                const char *name;
                const u32 *reg;

                DBG(" control: %pOFn, type: %s\n", np, of_node_get_device_type(np));

                /* Detect control type */
                if (of_node_is_type(np, "fan-rpm-control") ||
                    of_node_is_type(np, "fan-rpm"))
                        type = FCU_FAN_RPM;
                if (of_node_is_type(np, "fan-pwm-control") ||
                    of_node_is_type(np, "fan-pwm"))
                        type = FCU_FAN_PWM;
                /* Only care about fans for now */
                if (type == -1)
                        continue;

                /* Lookup for a matching location */
                loc = of_get_property(np, "location", NULL);
                reg = of_get_property(np, "reg", NULL);
                if (loc == NULL || reg == NULL)
                        continue;
                DBG(" matching location: %s, reg: 0x%08x\n", loc, *reg);

                for (i = 0; i < ARRAY_SIZE(loc_trans); i++) {
                        if (strncmp(loc, loc_trans[i].dt_name,
                                    strlen(loc_trans[i].dt_name)))
                                continue;
                        name = loc_trans[i].ct_name;

                        DBG(" location match, name: %s\n", name);

                        if (type == FCU_FAN_RPM)
                                id = ((*reg) - 0x10) / 2;
                        else
                                id = ((*reg) - 0x30) / 2;
                        if (id > 7) {
                                pr_warn("wf_fcu: Can't parse fan ID in device-tree for %pOF\n", np);
                                break;
                        }
                        wf_fcu_add_fan(pv, name, type, id);
                        break;
                }
        }
}

static void wf_fcu_default_fans(struct wf_fcu_priv *pv)
{
        /* We only support the default fans for PowerMac7,2 */
        if (!of_machine_is_compatible("PowerMac7,2"))
                return;

        wf_fcu_add_fan(pv, "backside-fan",      FCU_FAN_PWM, 1);
        wf_fcu_add_fan(pv, "drive-bay-fan",     FCU_FAN_RPM, 2);
        wf_fcu_add_fan(pv, "slots-fan",         FCU_FAN_PWM, 2);
        wf_fcu_add_fan(pv, "cpu-front-fan-0",   FCU_FAN_RPM, 3);
        wf_fcu_add_fan(pv, "cpu-rear-fan-0",    FCU_FAN_RPM, 4);
        wf_fcu_add_fan(pv, "cpu-front-fan-1",   FCU_FAN_RPM, 5);
        wf_fcu_add_fan(pv, "cpu-rear-fan-1",    FCU_FAN_RPM, 6);
}

static int wf_fcu_init_chip(struct wf_fcu_priv *pv)
{
        unsigned char buf = 0xff;
        int rc;

        rc = wf_fcu_write_reg(pv, 0xe, &buf, 1);
        if (rc < 0)
                return -EIO;
        rc = wf_fcu_write_reg(pv, 0x2e, &buf, 1);
        if (rc < 0)
                return -EIO;
        rc = wf_fcu_read_reg(pv, 0, &buf, 1);
        if (rc < 0)
                return -EIO;
        pv->rpm_shift = (buf == 1) ? 2 : 3;

        pr_debug("wf_fcu: FCU Initialized, RPM fan shift is %d\n",
                 pv->rpm_shift);

        return 0;
}

static int wf_fcu_probe(struct i2c_client *client)
{
        struct wf_fcu_priv *pv;

        pv = kzalloc_obj(*pv);
        if (!pv)
                return -ENOMEM;

        kref_init(&pv->ref);
        mutex_init(&pv->lock);
        INIT_LIST_HEAD(&pv->fan_list);
        pv->i2c = client;

        /*
         * First we must start the FCU which will query the
         * shift value to apply to RPMs
         */
        if (wf_fcu_init_chip(pv)) {
                pr_err("wf_fcu: Initialization failed !\n");
                kfree(pv);
                return -ENXIO;
        }

        /* First lookup fans in the device-tree */
        wf_fcu_lookup_fans(pv);

        /*
         * Older machines don't have the device-tree entries
         * we are looking for, just hard code the list
         */
        if (list_empty(&pv->fan_list))
                wf_fcu_default_fans(pv);

        /* Still no fans ? FAIL */
        if (list_empty(&pv->fan_list)) {
                pr_err("wf_fcu: Failed to find fans for your machine\n");
                kfree(pv);
                return -ENODEV;
        }

        dev_set_drvdata(&client->dev, pv);

        return 0;
}

static void wf_fcu_remove(struct i2c_client *client)
{
        struct wf_fcu_priv *pv = dev_get_drvdata(&client->dev);
        struct wf_fcu_fan *fan;

        while (!list_empty(&pv->fan_list)) {
                fan = list_first_entry(&pv->fan_list, struct wf_fcu_fan, link);
                list_del(&fan->link);
                wf_unregister_control(&fan->ctrl);
        }
        kref_put(&pv->ref, wf_fcu_release);
}

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

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

static struct i2c_driver wf_fcu_driver = {
        .driver = {
                .name   = "wf_fcu",
                .of_match_table = wf_fcu_of_id,
        },
        .probe          = wf_fcu_probe,
        .remove         = wf_fcu_remove,
        .id_table       = wf_fcu_id,
};

module_i2c_driver(wf_fcu_driver);

MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
MODULE_DESCRIPTION("FCU control objects for PowerMacs thermal control");
MODULE_LICENSE("GPL");