// SPDX-License-Identifier: GPL-2.0-only
/*
 * PISMO memory driver - http://www.pismoworld.org/
 *
 * For ARM Realview and Versatile platforms
 */
#include <linux/init.h>
#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/slab.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>
#include <linux/mutex.h>
#include <linux/mtd/physmap.h>
#include <linux/mtd/plat-ram.h>
#include <linux/mtd/pismo.h>

#define PISMO_NUM_CS    5

struct pismo_cs_block {
        u8      type;
        u8      width;
        __le16  access;
        __le32  size;
        u32     reserved[2];
        char    device[32];
} __packed;

struct pismo_eeprom {
        struct pismo_cs_block cs[PISMO_NUM_CS];
        char    board[15];
        u8      sum;
} __packed;

struct pismo_mem {
        phys_addr_t base;
        u32     size;
        u16     access;
        u8      width;
        u8      type;
};

struct pismo_data {
        struct i2c_client       *client;
        void                    (*vpp)(void *, int);
        void                    *vpp_data;
        struct platform_device  *dev[PISMO_NUM_CS];
};

static void pismo_set_vpp(struct platform_device *pdev, int on)
{
        struct i2c_client *client = to_i2c_client(pdev->dev.parent);
        struct pismo_data *pismo = i2c_get_clientdata(client);

        pismo->vpp(pismo->vpp_data, on);
}

static unsigned int pismo_width_to_bytes(unsigned int width)
{
        width &= 15;
        if (width > 2)
                return 0;
        return 1 << width;
}

static int pismo_eeprom_read(struct i2c_client *client, void *buf, u8 addr,
                             size_t size)
{
        int ret;
        struct i2c_msg msg[] = {
                {
                        .addr = client->addr,
                        .len = sizeof(addr),
                        .buf = &addr,
                }, {
                        .addr = client->addr,
                        .flags = I2C_M_RD,
                        .len = size,
                        .buf = buf,
                },
        };

        ret = i2c_transfer(client->adapter, msg, ARRAY_SIZE(msg));

        return ret == ARRAY_SIZE(msg) ? size : -EIO;
}

static int pismo_add_device(struct pismo_data *pismo, int i,
                            struct pismo_mem *region, const char *name,
                            void *pdata, size_t psize)
{
        struct platform_device *dev;
        struct resource res = { };
        phys_addr_t base = region->base;
        int ret;

        if (base == ~0)
                return -ENXIO;

        res.start = base;
        res.end = base + region->size - 1;
        res.flags = IORESOURCE_MEM;

        dev = platform_device_alloc(name, i);
        if (!dev)
                return -ENOMEM;
        dev->dev.parent = &pismo->client->dev;

        do {
                ret = platform_device_add_resources(dev, &res, 1);
                if (ret)
                        break;

                ret = platform_device_add_data(dev, pdata, psize);
                if (ret)
                        break;

                ret = platform_device_add(dev);
                if (ret)
                        break;

                pismo->dev[i] = dev;
                return 0;
        } while (0);

        platform_device_put(dev);
        return ret;
}

static int pismo_add_nor(struct pismo_data *pismo, int i,
                         struct pismo_mem *region)
{
        struct physmap_flash_data data = {
                .width = region->width,
        };

        if (pismo->vpp)
                data.set_vpp = pismo_set_vpp;

        return pismo_add_device(pismo, i, region, "physmap-flash",
                &data, sizeof(data));
}

static int pismo_add_sram(struct pismo_data *pismo, int i,
                          struct pismo_mem *region)
{
        struct platdata_mtd_ram data = {
                .bankwidth = region->width,
        };

        return pismo_add_device(pismo, i, region, "mtd-ram",
                &data, sizeof(data));
}

static void pismo_add_one(struct pismo_data *pismo, int i,
                          const struct pismo_cs_block *cs, phys_addr_t base)
{
        struct device *dev = &pismo->client->dev;
        struct pismo_mem region;

        region.base = base;
        region.type = cs->type;
        region.width = pismo_width_to_bytes(cs->width);
        region.access = le16_to_cpu(cs->access);
        region.size = le32_to_cpu(cs->size);

        if (region.width == 0) {
                dev_err(dev, "cs%u: bad width: %02x, ignoring\n", i, cs->width);
                return;
        }

        /*
         * FIXME: may need to the platforms memory controller here, but at
         * the moment we assume that it has already been correctly setup.
         * The memory controller can also tell us the base address as well.
         */

        dev_info(dev, "cs%u: %.32s: type %02x access %u00ps size %uK\n",
                i, cs->device, region.type, region.access, region.size / 1024);

        switch (region.type) {
        case 0:
                break;
        case 1:
                /* static DOC */
                break;
        case 2:
                /* static NOR */
                pismo_add_nor(pismo, i, &region);
                break;
        case 3:
                /* static RAM */
                pismo_add_sram(pismo, i, &region);
                break;
        }
}

static void pismo_remove(struct i2c_client *client)
{
        struct pismo_data *pismo = i2c_get_clientdata(client);
        int i;

        for (i = 0; i < ARRAY_SIZE(pismo->dev); i++)
                platform_device_unregister(pismo->dev[i]);

        kfree(pismo);
}

static int pismo_probe(struct i2c_client *client)
{
        struct pismo_pdata *pdata = client->dev.platform_data;
        struct pismo_eeprom eeprom;
        struct pismo_data *pismo;
        int ret, i;

        if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
                dev_err(&client->dev, "functionality mismatch\n");
                return -EIO;
        }

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

        pismo->client = client;
        if (pdata) {
                pismo->vpp = pdata->set_vpp;
                pismo->vpp_data = pdata->vpp_data;
        }
        i2c_set_clientdata(client, pismo);

        ret = pismo_eeprom_read(client, &eeprom, 0, sizeof(eeprom));
        if (ret < 0) {
                dev_err(&client->dev, "error reading EEPROM: %d\n", ret);
                goto exit_free;
        }

        dev_info(&client->dev, "%.15s board found\n", eeprom.board);

        for (i = 0; i < ARRAY_SIZE(eeprom.cs); i++)
                if (eeprom.cs[i].type != 0xff)
                        pismo_add_one(pismo, i, &eeprom.cs[i],
                                      pdata->cs_addrs[i]);

        return 0;

 exit_free:
        kfree(pismo);
        return ret;
}

static const struct i2c_device_id pismo_id[] = {
        { "pismo" },
        { },
};
MODULE_DEVICE_TABLE(i2c, pismo_id);

static struct i2c_driver pismo_driver = {
        .driver = {
                .name   = "pismo",
        },
        .probe          = pismo_probe,
        .remove         = pismo_remove,
        .id_table       = pismo_id,
};

static int __init pismo_init(void)
{
        BUILD_BUG_ON(sizeof(struct pismo_cs_block) != 48);
        BUILD_BUG_ON(sizeof(struct pismo_eeprom) != 256);

        return i2c_add_driver(&pismo_driver);
}
module_init(pismo_init);

static void __exit pismo_exit(void)
{
        i2c_del_driver(&pismo_driver);
}
module_exit(pismo_exit);

MODULE_AUTHOR("Russell King <linux@arm.linux.org.uk>");
MODULE_DESCRIPTION("PISMO memory driver");
MODULE_LICENSE("GPL");