// SPDX-License-Identifier: GPL-2.0-only
/*
 *      w1_ds2433.c - w1 family 23 (DS2433) & 43 (DS28EC20) eeprom driver
 *
 * Copyright (c) 2005 Ben Gardner <bgardner@wabtec.com>
 * Copyright (c) 2023 Marc Ferland <marc.ferland@sonatest.com>
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/device.h>
#include <linux/types.h>
#include <linux/delay.h>
#include <linux/slab.h>
#ifdef CONFIG_W1_SLAVE_DS2433_CRC
#include <linux/crc16.h>

#define CRC16_INIT              0
#define CRC16_VALID             0xb001

#endif

#include <linux/w1.h>

#define W1_EEPROM_DS2433        0x23
#define W1_EEPROM_DS28EC20      0x43

#define W1_EEPROM_DS2433_SIZE   512
#define W1_EEPROM_DS28EC20_SIZE 2560

#define W1_PAGE_SIZE            32
#define W1_PAGE_BITS            5
#define W1_PAGE_MASK            0x1F
#define W1_VALIDCRC_MAX         96

#define W1_F23_READ_EEPROM      0xF0
#define W1_F23_WRITE_SCRATCH    0x0F
#define W1_F23_READ_SCRATCH     0xAA
#define W1_F23_COPY_SCRATCH     0x55

struct ds2433_config {
        size_t eeprom_size;             /* eeprom size in bytes */
        unsigned int page_count;        /* number of 256 bits pages */
        unsigned int tprog;             /* time in ms for page programming */
};

static const struct ds2433_config config_f23 = {
        .eeprom_size = W1_EEPROM_DS2433_SIZE,
        .page_count = 16,
        .tprog = 5,
};

static const struct ds2433_config config_f43 = {
        .eeprom_size = W1_EEPROM_DS28EC20_SIZE,
        .page_count = 80,
        .tprog = 10,
};

struct w1_f23_data {
#ifdef CONFIG_W1_SLAVE_DS2433_CRC
        u8 *memory;
        DECLARE_BITMAP(validcrc, W1_VALIDCRC_MAX);
#endif
        const struct ds2433_config *cfg;
};

/*
 * Check the file size bounds and adjusts count as needed.
 * This would not be needed if the file size didn't reset to 0 after a write.
 */
static inline size_t w1_f23_fix_count(loff_t off, size_t count, size_t size)
{
        if (off > size)
                return 0;

        if ((off + count) > size)
                return (size - off);

        return count;
}

#ifdef CONFIG_W1_SLAVE_DS2433_CRC
static int w1_f23_refresh_block(struct w1_slave *sl, struct w1_f23_data *data,
                                int block)
{
        u8      wrbuf[3];
        int     off = block * W1_PAGE_SIZE;

        if (test_bit(block, data->validcrc))
                return 0;

        if (w1_reset_select_slave(sl)) {
                bitmap_zero(data->validcrc, data->cfg->page_count);
                return -EIO;
        }

        wrbuf[0] = W1_F23_READ_EEPROM;
        wrbuf[1] = off & 0xff;
        wrbuf[2] = off >> 8;
        w1_write_block(sl->master, wrbuf, 3);
        w1_read_block(sl->master, &data->memory[off], W1_PAGE_SIZE);

        /* cache the block if the CRC is valid */
        if (crc16(CRC16_INIT, &data->memory[off], W1_PAGE_SIZE) == CRC16_VALID)
                set_bit(block, data->validcrc);

        return 0;
}
#endif  /* CONFIG_W1_SLAVE_DS2433_CRC */

static ssize_t eeprom_read(struct file *filp, struct kobject *kobj,
                           const struct bin_attribute *bin_attr, char *buf,
                           loff_t off, size_t count)
{
        struct w1_slave *sl = kobj_to_w1_slave(kobj);
#ifdef CONFIG_W1_SLAVE_DS2433_CRC
        struct w1_f23_data *data = sl->family_data;
        int i, min_page, max_page;
#else
        u8 wrbuf[3];
#endif

        count = w1_f23_fix_count(off, count, bin_attr->size);
        if (!count)
                return 0;

        mutex_lock(&sl->master->bus_mutex);

#ifdef CONFIG_W1_SLAVE_DS2433_CRC

        min_page = (off >> W1_PAGE_BITS);
        max_page = (off + count - 1) >> W1_PAGE_BITS;
        for (i = min_page; i <= max_page; i++) {
                if (w1_f23_refresh_block(sl, data, i)) {
                        count = -EIO;
                        goto out_up;
                }
        }
        memcpy(buf, &data->memory[off], count);

#else   /* CONFIG_W1_SLAVE_DS2433_CRC */

        /* read directly from the EEPROM */
        if (w1_reset_select_slave(sl)) {
                count = -EIO;
                goto out_up;
        }

        wrbuf[0] = W1_F23_READ_EEPROM;
        wrbuf[1] = off & 0xff;
        wrbuf[2] = off >> 8;
        w1_write_block(sl->master, wrbuf, 3);
        w1_read_block(sl->master, buf, count);

#endif  /* CONFIG_W1_SLAVE_DS2433_CRC */

out_up:
        mutex_unlock(&sl->master->bus_mutex);

        return count;
}

/**
 * w1_f23_write() - Writes to the scratchpad and reads it back for verification.
 * @sl:         The slave structure
 * @addr:       Address for the write
 * @len:        length must be <= (W1_PAGE_SIZE - (addr & W1_PAGE_MASK))
 * @data:       The data to write
 *
 * Then copies the scratchpad to EEPROM.
 * The data must be on one page.
 * The master must be locked.
 *
 * Return:      0=Success, -1=failure
 */
static int w1_f23_write(struct w1_slave *sl, int addr, int len, const u8 *data)
{
        struct w1_f23_data *f23 = sl->family_data;
        u8 wrbuf[4];
        u8 rdbuf[W1_PAGE_SIZE + 3];
        u8 es = (addr + len - 1) & 0x1f;

        /* Write the data to the scratchpad */
        if (w1_reset_select_slave(sl))
                return -1;

        wrbuf[0] = W1_F23_WRITE_SCRATCH;
        wrbuf[1] = addr & 0xff;
        wrbuf[2] = addr >> 8;

        w1_write_block(sl->master, wrbuf, 3);
        w1_write_block(sl->master, data, len);

        /* Read the scratchpad and verify */
        if (w1_reset_select_slave(sl))
                return -1;

        w1_write_8(sl->master, W1_F23_READ_SCRATCH);
        w1_read_block(sl->master, rdbuf, len + 3);

        /* Compare what was read against the data written */
        if ((rdbuf[0] != wrbuf[1]) || (rdbuf[1] != wrbuf[2]) ||
            (rdbuf[2] != es) || (memcmp(data, &rdbuf[3], len) != 0))
                return -1;

        /* Copy the scratchpad to EEPROM */
        if (w1_reset_select_slave(sl))
                return -1;

        wrbuf[0] = W1_F23_COPY_SCRATCH;
        wrbuf[3] = es;
        w1_write_block(sl->master, wrbuf, 4);

        /* Sleep for tprog ms to wait for the write to complete */
        msleep(f23->cfg->tprog);

        /* Reset the bus to wake up the EEPROM (this may not be needed) */
        w1_reset_bus(sl->master);
#ifdef CONFIG_W1_SLAVE_DS2433_CRC
        clear_bit(addr >> W1_PAGE_BITS, f23->validcrc);
#endif
        return 0;
}

static ssize_t eeprom_write(struct file *filp, struct kobject *kobj,
                            const struct bin_attribute *bin_attr, char *buf,
                            loff_t off, size_t count)
{
        struct w1_slave *sl = kobj_to_w1_slave(kobj);
        int addr, len, idx;

        count = w1_f23_fix_count(off, count, bin_attr->size);
        if (!count)
                return 0;

#ifdef CONFIG_W1_SLAVE_DS2433_CRC
        /* can only write full blocks in cached mode */
        if ((off & W1_PAGE_MASK) || (count & W1_PAGE_MASK)) {
                dev_err(&sl->dev, "invalid offset/count off=%d cnt=%zd\n",
                        (int)off, count);
                return -EINVAL;
        }

        /* make sure the block CRCs are valid */
        for (idx = 0; idx < count; idx += W1_PAGE_SIZE) {
                if (crc16(CRC16_INIT, &buf[idx], W1_PAGE_SIZE) != CRC16_VALID) {
                        dev_err(&sl->dev, "bad CRC at offset %d\n", (int)off);
                        return -EINVAL;
                }
        }
#endif  /* CONFIG_W1_SLAVE_DS2433_CRC */

        mutex_lock(&sl->master->bus_mutex);

        /* Can only write data to one page at a time */
        idx = 0;
        while (idx < count) {
                addr = off + idx;
                len = W1_PAGE_SIZE - (addr & W1_PAGE_MASK);
                if (len > (count - idx))
                        len = count - idx;

                if (w1_f23_write(sl, addr, len, &buf[idx]) < 0) {
                        count = -EIO;
                        goto out_up;
                }
                idx += len;
        }

out_up:
        mutex_unlock(&sl->master->bus_mutex);

        return count;
}

static const struct bin_attribute bin_attr_f23_eeprom = {
        .attr = { .name = "eeprom", .mode = 0644 },
        .read = eeprom_read,
        .write = eeprom_write,
        .size = W1_EEPROM_DS2433_SIZE,
};

static const struct bin_attribute bin_attr_f43_eeprom = {
        .attr = { .name = "eeprom", .mode = 0644 },
        .read = eeprom_read,
        .write = eeprom_write,
        .size = W1_EEPROM_DS28EC20_SIZE,
};

static const struct bin_attribute *const w1_f23_bin_attributes[] = {
        &bin_attr_f23_eeprom,
        NULL,
};

static const struct attribute_group w1_f23_group = {
        .bin_attrs = w1_f23_bin_attributes,
};

static const struct attribute_group *w1_f23_groups[] = {
        &w1_f23_group,
        NULL,
};

static const struct bin_attribute *const w1_f43_bin_attributes[] = {
        &bin_attr_f43_eeprom,
        NULL,
};

static const struct attribute_group w1_f43_group = {
        .bin_attrs = w1_f43_bin_attributes,
};

static const struct attribute_group *w1_f43_groups[] = {
        &w1_f43_group,
        NULL,
};

static int w1_f23_add_slave(struct w1_slave *sl)
{
        struct w1_f23_data *data;

        data = kzalloc_obj(struct w1_f23_data);
        if (!data)
                return -ENOMEM;

        switch (sl->family->fid) {
        case W1_EEPROM_DS2433:
                data->cfg = &config_f23;
                break;
        case W1_EEPROM_DS28EC20:
                data->cfg = &config_f43;
                break;
        }

#ifdef CONFIG_W1_SLAVE_DS2433_CRC
        if (data->cfg->page_count > W1_VALIDCRC_MAX) {
                dev_err(&sl->dev, "page count too big for crc bitmap\n");
                kfree(data);
                return -EINVAL;
        }
        data->memory = kzalloc(data->cfg->eeprom_size, GFP_KERNEL);
        if (!data->memory) {
                kfree(data);
                return -ENOMEM;
        }
        bitmap_zero(data->validcrc, data->cfg->page_count);
#endif /* CONFIG_W1_SLAVE_DS2433_CRC */
        sl->family_data = data;

        return 0;
}

static void w1_f23_remove_slave(struct w1_slave *sl)
{
        struct w1_f23_data *data = sl->family_data;
        sl->family_data = NULL;
#ifdef CONFIG_W1_SLAVE_DS2433_CRC
        kfree(data->memory);
#endif /* CONFIG_W1_SLAVE_DS2433_CRC */
        kfree(data);
}

static const struct w1_family_ops w1_f23_fops = {
        .add_slave      = w1_f23_add_slave,
        .remove_slave   = w1_f23_remove_slave,
        .groups         = w1_f23_groups,
};

static const struct w1_family_ops w1_f43_fops = {
        .add_slave      = w1_f23_add_slave,
        .remove_slave   = w1_f23_remove_slave,
        .groups         = w1_f43_groups,
};

static struct w1_family w1_family_23 = {
        .fid = W1_EEPROM_DS2433,
        .fops = &w1_f23_fops,
};

static struct w1_family w1_family_43 = {
        .fid = W1_EEPROM_DS28EC20,
        .fops = &w1_f43_fops,
};

static int __init w1_ds2433_init(void)
{
        int err;

        err = w1_register_family(&w1_family_23);
        if (err)
                return err;

        err = w1_register_family(&w1_family_43);
        if (err)
                goto err_43;

        return 0;

err_43:
        w1_unregister_family(&w1_family_23);
        return err;
}

static void __exit w1_ds2433_exit(void)
{
        w1_unregister_family(&w1_family_23);
        w1_unregister_family(&w1_family_43);
}

module_init(w1_ds2433_init);
module_exit(w1_ds2433_exit);

MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>");
MODULE_AUTHOR("Marc Ferland <marc.ferland@sonatest.com>");
MODULE_DESCRIPTION("w1 family 23/43 driver for DS2433 (4kb) and DS28EC20 (20kb)");
MODULE_LICENSE("GPL");
MODULE_ALIAS("w1-family-" __stringify(W1_EEPROM_DS2433));
MODULE_ALIAS("w1-family-" __stringify(W1_EEPROM_DS28EC20));