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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* ee1004 - driver for DDR4 SPD EEPROMs
*
* Copyright (C) 2017-2019 Jean Delvare
*
* Based on the at24 driver:
* Copyright (C) 2005-2007 David Brownell
* Copyright (C) 2008 Wolfram Sang, Pengutronix
*/
#include <linux/mfd/qnap-mcu.h>
#include <linux/module.h>
#include <linux/nvmem-provider.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
/* Determined by trial and error until read anomalies appeared */
#define QNAP_MCU_EEPROM_SIZE 256
#define QNAP_MCU_EEPROM_BLOCK_SIZE 32
static int qnap_mcu_eeprom_read_block(struct qnap_mcu *mcu, unsigned int offset,
void *val, size_t bytes)
{
const u8 cmd[] = { 0xf7, 0xa1, offset, bytes };
u8 *reply;
int ret = 0;
reply = kzalloc(bytes + sizeof(cmd), GFP_KERNEL);
if (!reply)
return -ENOMEM;
ret = qnap_mcu_exec(mcu, cmd, sizeof(cmd), reply, bytes + sizeof(cmd));
if (ret)
goto out;
/* First bytes must mirror the sent command */
if (memcmp(cmd, reply, sizeof(cmd))) {
ret = -EIO;
goto out;
}
memcpy(val, reply + sizeof(cmd), bytes);
out:
kfree(reply);
return ret;
}
static int qnap_mcu_eeprom_read(void *priv, unsigned int offset, void *val, size_t bytes)
{
struct qnap_mcu *mcu = priv;
int pos = 0, ret;
u8 *buf = val;
if (unlikely(!bytes))
return 0;
while (bytes > 0) {
size_t to_read = (bytes > QNAP_MCU_EEPROM_BLOCK_SIZE) ?
QNAP_MCU_EEPROM_BLOCK_SIZE : bytes;
ret = qnap_mcu_eeprom_read_block(mcu, offset + pos, &buf[pos], to_read);
if (ret < 0)
return ret;
pos += to_read;
bytes -= to_read;
}
return 0;
}
static int qnap_mcu_eeprom_probe(struct platform_device *pdev)
{
struct qnap_mcu *mcu = dev_get_drvdata(pdev->dev.parent);
struct nvmem_config nvcfg = {};
struct nvmem_device *ndev;
nvcfg.dev = &pdev->dev;
nvcfg.of_node = pdev->dev.parent->of_node;
nvcfg.name = dev_name(&pdev->dev);
nvcfg.id = NVMEM_DEVID_NONE;
nvcfg.owner = THIS_MODULE;
nvcfg.type = NVMEM_TYPE_EEPROM;
nvcfg.read_only = true;
nvcfg.root_only = false;
nvcfg.reg_read = qnap_mcu_eeprom_read;
nvcfg.size = QNAP_MCU_EEPROM_SIZE,
nvcfg.word_size = 1,
nvcfg.stride = 1,
nvcfg.priv = mcu,
ndev = devm_nvmem_register(&pdev->dev, &nvcfg);
if (IS_ERR(ndev))
return PTR_ERR(ndev);
return 0;
}
static struct platform_driver qnap_mcu_eeprom_driver = {
.probe = qnap_mcu_eeprom_probe,
.driver = {
.name = "qnap-mcu-eeprom",
},
};
module_platform_driver(qnap_mcu_eeprom_driver);
MODULE_AUTHOR("Heiko Stuebner <heiko@sntech.de>");
MODULE_DESCRIPTION("QNAP MCU EEPROM driver");
MODULE_LICENSE("GPL");
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