/*
   * Windfarm PowerMac thermal control. FCU fan control
   *
   * Copyright 2012 Benjamin Herrenschmidt, IBM Corp.
   *
   * Released under the term of the GNU GPL v2.
   */
  #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/prom.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
  ",
  	    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
  ",
  	    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(sizeof(*fan), GFP_KERNEL);
  	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
  ", 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 = NULL, *fcu = pv->i2c->dev.of_node;
  	int i;
  
  	DBG("Looking up FCU controls in device-tree...
  ");
  
  	while ((np = of_get_next_child(fcu, np)) != NULL) {
  		int id, type = -1;
  		const char *loc;
  		const char *name;
  		const u32 *reg;
  
  		DBG(" control: %s, type: %s
  ", np->name, np->type);
  
  		/* Detect control type */
  		if (!strcmp(np->type, "fan-rpm-control") ||
  		    !strcmp(np->type, "fan-rpm"))
  			type = FCU_FAN_RPM;
  		if (!strcmp(np->type, "fan-pwm-control") ||
  		    !strcmp(np->type, "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
  ", 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
  ", name);
  
  			if (type == FCU_FAN_RPM)
  				id = ((*reg) - 0x10) / 2;
  			else
  				id = ((*reg) - 0x30) / 2;
  			if (id > 7) {
  				pr_warning("wf_fcu: Can't parse "
  				       "fan ID in device-tree for %s
  ",
  					   np->full_name);
  				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
  ",
  		 pv->rpm_shift);
  
  	return 0;
  }
  
  static int wf_fcu_probe(struct i2c_client *client,
  			const struct i2c_device_id *id)
  {
  	struct wf_fcu_priv *pv;
  
  	pv = kzalloc(sizeof(*pv), GFP_KERNEL);
  	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 !
  ");
  		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
  ");
  		kfree(pv);
  		return -ENODEV;
  	}
  
  	dev_set_drvdata(&client->dev, pv);
  
  	return 0;
  }
  
  static int 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);
  	return 0;
  }
  
  static const struct i2c_device_id wf_fcu_id[] = {
  	{ "MAC,fcu", 0 },
  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, wf_fcu_id);
  
  static struct i2c_driver wf_fcu_driver = {
  	.driver = {
  		.name	= "wf_fcu",
  	},
  	.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");