// SPDX-License-Identifier: GPL-2.0-only
/* bbc_i2c.c: I2C low-level driver for BBC device on UltraSPARC-III
 *            platforms.
 *
 * Copyright (C) 2001, 2008 David S. Miller (davem@davemloft.net)
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <asm/bbc.h>
#include <asm/io.h>

#include "bbc_i2c.h"

/* Convert this driver to use i2c bus layer someday... */
#define I2C_PCF_PIN     0x80
#define I2C_PCF_ESO     0x40
#define I2C_PCF_ES1     0x20
#define I2C_PCF_ES2     0x10
#define I2C_PCF_ENI     0x08
#define I2C_PCF_STA     0x04
#define I2C_PCF_STO     0x02
#define I2C_PCF_ACK     0x01

#define I2C_PCF_START    (I2C_PCF_PIN | I2C_PCF_ESO | I2C_PCF_ENI | I2C_PCF_STA | I2C_PCF_ACK)
#define I2C_PCF_STOP     (I2C_PCF_PIN | I2C_PCF_ESO | I2C_PCF_STO | I2C_PCF_ACK)
#define I2C_PCF_REPSTART (              I2C_PCF_ESO | I2C_PCF_STA | I2C_PCF_ACK)
#define I2C_PCF_IDLE     (I2C_PCF_PIN | I2C_PCF_ESO               | I2C_PCF_ACK)

#define I2C_PCF_INI 0x40   /* 1 if not initialized */
#define I2C_PCF_STS 0x20
#define I2C_PCF_BER 0x10
#define I2C_PCF_AD0 0x08
#define I2C_PCF_LRB 0x08
#define I2C_PCF_AAS 0x04
#define I2C_PCF_LAB 0x02
#define I2C_PCF_BB  0x01

/* The BBC devices have two I2C controllers.  The first I2C controller
 * connects mainly to configuration proms (NVRAM, cpu configuration,
 * dimm types, etc.).  Whereas the second I2C controller connects to
 * environmental control devices such as fans and temperature sensors.
 * The second controller also connects to the smartcard reader, if present.
 */

static void set_device_claimage(struct bbc_i2c_bus *bp, struct platform_device *op, int val)
{
        int i;

        for (i = 0; i < NUM_CHILDREN; i++) {
                if (bp->devs[i].device == op) {
                        bp->devs[i].client_claimed = val;
                        return;
                }
        }
}

#define claim_device(BP,ECHILD)         set_device_claimage(BP,ECHILD,1)
#define release_device(BP,ECHILD)       set_device_claimage(BP,ECHILD,0)

struct platform_device *bbc_i2c_getdev(struct bbc_i2c_bus *bp, int index)
{
        struct platform_device *op = NULL;
        int curidx = 0, i;

        for (i = 0; i < NUM_CHILDREN; i++) {
                if (!(op = bp->devs[i].device))
                        break;
                if (curidx == index)
                        goto out;
                op = NULL;
                curidx++;
        }

out:
        if (curidx == index)
                return op;
        return NULL;
}

struct bbc_i2c_client *bbc_i2c_attach(struct bbc_i2c_bus *bp, struct platform_device *op)
{
        struct bbc_i2c_client *client;
        const u32 *reg;

        client = kzalloc_obj(*client);
        if (!client)
                return NULL;
        client->bp = bp;
        client->op = op;

        reg = of_get_property(op->dev.of_node, "reg", NULL);
        if (!reg) {
                kfree(client);
                return NULL;
        }

        client->bus = reg[0];
        client->address = reg[1];

        claim_device(bp, op);

        return client;
}

void bbc_i2c_detach(struct bbc_i2c_client *client)
{
        struct bbc_i2c_bus *bp = client->bp;
        struct platform_device *op = client->op;

        release_device(bp, op);
        kfree(client);
}

static int wait_for_pin(struct bbc_i2c_bus *bp, u8 *status)
{
        DECLARE_WAITQUEUE(wait, current);
        int limit = 32;
        int ret = 1;

        bp->waiting = 1;
        add_wait_queue(&bp->wq, &wait);
        while (limit-- > 0) {
                long val;

                val = wait_event_interruptible_timeout(
                                bp->wq,
                                (((*status = readb(bp->i2c_control_regs + 0))
                                  & I2C_PCF_PIN) == 0),
                                msecs_to_jiffies(250));
                if (val > 0) {
                        ret = 0;
                        break;
                }
        }
        remove_wait_queue(&bp->wq, &wait);
        bp->waiting = 0;

        return ret;
}

int bbc_i2c_writeb(struct bbc_i2c_client *client, unsigned char val, int off)
{
        struct bbc_i2c_bus *bp = client->bp;
        int address = client->address;
        u8 status;
        int ret = -1;

        if (bp->i2c_bussel_reg != NULL)
                writeb(client->bus, bp->i2c_bussel_reg);

        writeb(address, bp->i2c_control_regs + 0x1);
        writeb(I2C_PCF_START, bp->i2c_control_regs + 0x0);
        if (wait_for_pin(bp, &status))
                goto out;

        writeb(off, bp->i2c_control_regs + 0x1);
        if (wait_for_pin(bp, &status) ||
            (status & I2C_PCF_LRB) != 0)
                goto out;

        writeb(val, bp->i2c_control_regs + 0x1);
        if (wait_for_pin(bp, &status))
                goto out;

        ret = 0;

out:
        writeb(I2C_PCF_STOP, bp->i2c_control_regs + 0x0);
        return ret;
}

int bbc_i2c_readb(struct bbc_i2c_client *client, unsigned char *byte, int off)
{
        struct bbc_i2c_bus *bp = client->bp;
        unsigned char address = client->address, status;
        int ret = -1;

        if (bp->i2c_bussel_reg != NULL)
                writeb(client->bus, bp->i2c_bussel_reg);

        writeb(address, bp->i2c_control_regs + 0x1);
        writeb(I2C_PCF_START, bp->i2c_control_regs + 0x0);
        if (wait_for_pin(bp, &status))
                goto out;

        writeb(off, bp->i2c_control_regs + 0x1);
        if (wait_for_pin(bp, &status) ||
            (status & I2C_PCF_LRB) != 0)
                goto out;

        writeb(I2C_PCF_STOP, bp->i2c_control_regs + 0x0);

        address |= 0x1; /* READ */

        writeb(address, bp->i2c_control_regs + 0x1);
        writeb(I2C_PCF_START, bp->i2c_control_regs + 0x0);
        if (wait_for_pin(bp, &status))
                goto out;

        /* Set PIN back to one so the device sends the first
         * byte.
         */
        (void) readb(bp->i2c_control_regs + 0x1);
        if (wait_for_pin(bp, &status))
                goto out;

        writeb(I2C_PCF_ESO | I2C_PCF_ENI, bp->i2c_control_regs + 0x0);
        *byte = readb(bp->i2c_control_regs + 0x1);
        if (wait_for_pin(bp, &status))
                goto out;

        ret = 0;

out:
        writeb(I2C_PCF_STOP, bp->i2c_control_regs + 0x0);
        (void) readb(bp->i2c_control_regs + 0x1);

        return ret;
}

int bbc_i2c_write_buf(struct bbc_i2c_client *client,
                      char *buf, int len, int off)
{
        int ret = 0;

        while (len > 0) {
                ret = bbc_i2c_writeb(client, *buf, off);
                if (ret < 0)
                        break;
                len--;
                buf++;
                off++;
        }
        return ret;
}

int bbc_i2c_read_buf(struct bbc_i2c_client *client,
                     char *buf, int len, int off)
{
        int ret = 0;

        while (len > 0) {
                ret = bbc_i2c_readb(client, buf, off);
                if (ret < 0)
                        break;
                len--;
                buf++;
                off++;
        }

        return ret;
}

EXPORT_SYMBOL(bbc_i2c_getdev);
EXPORT_SYMBOL(bbc_i2c_attach);
EXPORT_SYMBOL(bbc_i2c_detach);
EXPORT_SYMBOL(bbc_i2c_writeb);
EXPORT_SYMBOL(bbc_i2c_readb);
EXPORT_SYMBOL(bbc_i2c_write_buf);
EXPORT_SYMBOL(bbc_i2c_read_buf);

static irqreturn_t bbc_i2c_interrupt(int irq, void *dev_id)
{
        struct bbc_i2c_bus *bp = dev_id;

        /* PIN going from set to clear is the only event which
         * makes the i2c assert an interrupt.
         */
        if (bp->waiting &&
            !(readb(bp->i2c_control_regs + 0x0) & I2C_PCF_PIN))
                wake_up_interruptible(&bp->wq);

        return IRQ_HANDLED;
}

static void reset_one_i2c(struct bbc_i2c_bus *bp)
{
        writeb(I2C_PCF_PIN, bp->i2c_control_regs + 0x0);
        writeb(bp->own, bp->i2c_control_regs + 0x1);
        writeb(I2C_PCF_PIN | I2C_PCF_ES1, bp->i2c_control_regs + 0x0);
        writeb(bp->clock, bp->i2c_control_regs + 0x1);
        writeb(I2C_PCF_IDLE, bp->i2c_control_regs + 0x0);
}

static struct bbc_i2c_bus * attach_one_i2c(struct platform_device *op, int index)
{
        struct bbc_i2c_bus *bp;
        struct device_node *dp;
        int entry;

        bp = kzalloc_obj(*bp);
        if (!bp)
                return NULL;

        INIT_LIST_HEAD(&bp->temps);
        INIT_LIST_HEAD(&bp->fans);

        bp->i2c_control_regs = of_ioremap(&op->resource[0], 0, 0x2, "bbc_i2c_regs");
        if (!bp->i2c_control_regs)
                goto fail;

        if (op->num_resources == 2) {
                bp->i2c_bussel_reg = of_ioremap(&op->resource[1], 0, 0x1, "bbc_i2c_bussel");
                if (!bp->i2c_bussel_reg)
                        goto fail;
        }

        bp->waiting = 0;
        init_waitqueue_head(&bp->wq);
        if (request_irq(op->archdata.irqs[0], bbc_i2c_interrupt,
                        IRQF_SHARED, "bbc_i2c", bp))
                goto fail;

        bp->index = index;
        bp->op = op;

        spin_lock_init(&bp->lock);

        entry = 0;
        for (dp = op->dev.of_node->child;
             dp && entry < 8;
             dp = dp->sibling, entry++) {
                struct platform_device *child_op;

                child_op = of_find_device_by_node(dp);
                bp->devs[entry].device = child_op;
                bp->devs[entry].client_claimed = 0;
        }

        writeb(I2C_PCF_PIN, bp->i2c_control_regs + 0x0);
        bp->own = readb(bp->i2c_control_regs + 0x01);
        writeb(I2C_PCF_PIN | I2C_PCF_ES1, bp->i2c_control_regs + 0x0);
        bp->clock = readb(bp->i2c_control_regs + 0x01);

        printk(KERN_INFO "i2c-%d: Regs at %p, %d devices, own %02x, clock %02x.\n",
               bp->index, bp->i2c_control_regs, entry, bp->own, bp->clock);

        reset_one_i2c(bp);

        return bp;

fail:
        if (bp->i2c_bussel_reg)
                of_iounmap(&op->resource[1], bp->i2c_bussel_reg, 1);
        if (bp->i2c_control_regs)
                of_iounmap(&op->resource[0], bp->i2c_control_regs, 2);
        kfree(bp);
        return NULL;
}

static int bbc_i2c_probe(struct platform_device *op)
{
        struct bbc_i2c_bus *bp;
        int err, index = 0;

        bp = attach_one_i2c(op, index);
        if (!bp)
                return -EINVAL;

        err = bbc_envctrl_init(bp);
        if (err) {
                free_irq(op->archdata.irqs[0], bp);
                if (bp->i2c_bussel_reg)
                        of_iounmap(&op->resource[0], bp->i2c_bussel_reg, 1);
                if (bp->i2c_control_regs)
                        of_iounmap(&op->resource[1], bp->i2c_control_regs, 2);
                kfree(bp);
        } else {
                dev_set_drvdata(&op->dev, bp);
        }

        return err;
}

static void bbc_i2c_remove(struct platform_device *op)
{
        struct bbc_i2c_bus *bp = dev_get_drvdata(&op->dev);

        bbc_envctrl_cleanup(bp);

        free_irq(op->archdata.irqs[0], bp);

        if (bp->i2c_bussel_reg)
                of_iounmap(&op->resource[0], bp->i2c_bussel_reg, 1);
        if (bp->i2c_control_regs)
                of_iounmap(&op->resource[1], bp->i2c_control_regs, 2);

        kfree(bp);
}

static const struct of_device_id bbc_i2c_match[] = {
        {
                .name = "i2c",
                .compatible = "SUNW,bbc-i2c",
        },
        {},
};
MODULE_DEVICE_TABLE(of, bbc_i2c_match);

static struct platform_driver bbc_i2c_driver = {
        .driver = {
                .name = "bbc_i2c",
                .of_match_table = bbc_i2c_match,
        },
        .probe          = bbc_i2c_probe,
        .remove         = bbc_i2c_remove,
};

module_platform_driver(bbc_i2c_driver);

MODULE_DESCRIPTION("UltraSPARC-III bootbus i2c controller driver");
MODULE_LICENSE("GPL");