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// SPDX-License-Identifier: GPL-2.0-only
//
// Copyright 2020 Google Inc
// Copyright 2025 Linaro Ltd.
//
// NVMEM driver for Maxim MAX77759
#include <linux/dev_printk.h>
#include <linux/device.h>
#include <linux/device/driver.h>
#include <linux/err.h>
#include <linux/mfd/max77759.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/nvmem-provider.h>
#include <linux/overflow.h>
#include <linux/platform_device.h>
#include <linux/string.h>
#define MAX77759_NVMEM_OPCODE_HEADER_LEN 3
/*
* NVMEM commands have a three byte header (which becomes part of the command),
* so we need to subtract that.
*/
#define MAX77759_NVMEM_SIZE (MAX77759_MAXQ_OPCODE_MAXLENGTH \
- MAX77759_NVMEM_OPCODE_HEADER_LEN)
struct max77759_nvmem {
struct device *dev;
struct max77759 *max77759;
};
static int max77759_nvmem_reg_read(void *priv, unsigned int offset,
void *val, size_t bytes)
{
struct max77759_nvmem *nvmem = priv;
DEFINE_FLEX(struct max77759_maxq_command, cmd, cmd, length,
MAX77759_NVMEM_OPCODE_HEADER_LEN);
DEFINE_FLEX(struct max77759_maxq_response, rsp, rsp, length,
MAX77759_MAXQ_OPCODE_MAXLENGTH);
int ret;
cmd->cmd[0] = MAX77759_MAXQ_OPCODE_USER_SPACE_READ;
cmd->cmd[1] = offset;
cmd->cmd[2] = bytes;
rsp->length = bytes + MAX77759_NVMEM_OPCODE_HEADER_LEN;
ret = max77759_maxq_command(nvmem->max77759, cmd, rsp);
if (ret < 0)
return ret;
if (memcmp(cmd->cmd, rsp->rsp, MAX77759_NVMEM_OPCODE_HEADER_LEN)) {
dev_warn(nvmem->dev, "protocol error (read)\n");
return -EIO;
}
memcpy(val, &rsp->rsp[MAX77759_NVMEM_OPCODE_HEADER_LEN], bytes);
return 0;
}
static int max77759_nvmem_reg_write(void *priv, unsigned int offset,
void *val, size_t bytes)
{
struct max77759_nvmem *nvmem = priv;
DEFINE_FLEX(struct max77759_maxq_command, cmd, cmd, length,
MAX77759_MAXQ_OPCODE_MAXLENGTH);
DEFINE_FLEX(struct max77759_maxq_response, rsp, rsp, length,
MAX77759_MAXQ_OPCODE_MAXLENGTH);
int ret;
cmd->cmd[0] = MAX77759_MAXQ_OPCODE_USER_SPACE_WRITE;
cmd->cmd[1] = offset;
cmd->cmd[2] = bytes;
memcpy(&cmd->cmd[MAX77759_NVMEM_OPCODE_HEADER_LEN], val, bytes);
cmd->length = bytes + MAX77759_NVMEM_OPCODE_HEADER_LEN;
rsp->length = cmd->length;
ret = max77759_maxq_command(nvmem->max77759, cmd, rsp);
if (ret < 0)
return ret;
if (memcmp(cmd->cmd, rsp->rsp, cmd->length)) {
dev_warn(nvmem->dev, "protocol error (write)\n");
return -EIO;
}
return 0;
}
static int max77759_nvmem_probe(struct platform_device *pdev)
{
struct nvmem_config config = {
.dev = &pdev->dev,
.name = dev_name(&pdev->dev),
.id = NVMEM_DEVID_NONE,
.type = NVMEM_TYPE_EEPROM,
.ignore_wp = true,
.size = MAX77759_NVMEM_SIZE,
.word_size = sizeof(u8),
.stride = sizeof(u8),
.reg_read = max77759_nvmem_reg_read,
.reg_write = max77759_nvmem_reg_write,
};
struct max77759_nvmem *nvmem;
nvmem = devm_kzalloc(&pdev->dev, sizeof(*nvmem), GFP_KERNEL);
if (!nvmem)
return -ENOMEM;
nvmem->dev = &pdev->dev;
nvmem->max77759 = dev_get_drvdata(pdev->dev.parent);
config.priv = nvmem;
return PTR_ERR_OR_ZERO(devm_nvmem_register(config.dev, &config));
}
static const struct of_device_id max77759_nvmem_of_id[] = {
{ .compatible = "maxim,max77759-nvmem", },
{ }
};
MODULE_DEVICE_TABLE(of, max77759_nvmem_of_id);
static const struct platform_device_id max77759_nvmem_platform_id[] = {
{ "max77759-nvmem", },
{ }
};
MODULE_DEVICE_TABLE(platform, max77759_nvmem_platform_id);
static struct platform_driver max77759_nvmem_driver = {
.driver = {
.name = "max77759-nvmem",
.probe_type = PROBE_PREFER_ASYNCHRONOUS,
.of_match_table = max77759_nvmem_of_id,
},
.probe = max77759_nvmem_probe,
.id_table = max77759_nvmem_platform_id,
};
module_platform_driver(max77759_nvmem_driver);
MODULE_AUTHOR("André Draszik <andre.draszik@linaro.org>");
MODULE_DESCRIPTION("NVMEM driver for Maxim MAX77759");
MODULE_LICENSE("GPL");
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