linux/drivers/nvmem/rave-sp-eeprom.c
Rafał Miłecki 2cc3b37f5b nvmem: add explicit config option to read old syntax fixed OF cells
Binding for fixed NVMEM cells defined directly as NVMEM device subnodes
has been deprecated. It has been replaced by the "fixed-layout" NVMEM
layout binding.

New syntax is meant to be clearer and should help avoiding imprecise
bindings.

NVMEM subsystem already supports the new binding. It should be a good
idea to limit support for old syntax to existing drivers that actually
support & use it (we can't break backward compatibility!). That way we
additionally encourage new bindings & drivers to ignore deprecated
binding.

It wasn't clear (to me) if rtc and w1 code actually uses old syntax
fixed cells. I enabled them to don't risk any breakage.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
[for meson-{efuse,mx-efuse}.c]
Acked-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
[for mtk-efuse.c, nvmem/core.c, nvmem-provider.h]
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
[MT8192, MT8195 Chromebooks]
Tested-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
[for microchip-otpc.c]
Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com>
[SAMA7G5-EK]
Tested-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20231020105545.216052-3-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-10-21 19:19:06 +02:00

363 lines
9.4 KiB
C

// SPDX-License-Identifier: GPL-2.0+
/*
* EEPROM driver for RAVE SP
*
* Copyright (C) 2018 Zodiac Inflight Innovations
*
*/
#include <linux/kernel.h>
#include <linux/mfd/rave-sp.h>
#include <linux/module.h>
#include <linux/nvmem-provider.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/sizes.h>
/**
* enum rave_sp_eeprom_access_type - Supported types of EEPROM access
*
* @RAVE_SP_EEPROM_WRITE: EEPROM write
* @RAVE_SP_EEPROM_READ: EEPROM read
*/
enum rave_sp_eeprom_access_type {
RAVE_SP_EEPROM_WRITE = 0,
RAVE_SP_EEPROM_READ = 1,
};
/**
* enum rave_sp_eeprom_header_size - EEPROM command header sizes
*
* @RAVE_SP_EEPROM_HEADER_SMALL: EEPROM header size for "small" devices (< 8K)
* @RAVE_SP_EEPROM_HEADER_BIG: EEPROM header size for "big" devices (> 8K)
*/
enum rave_sp_eeprom_header_size {
RAVE_SP_EEPROM_HEADER_SMALL = 4U,
RAVE_SP_EEPROM_HEADER_BIG = 5U,
};
#define RAVE_SP_EEPROM_HEADER_MAX RAVE_SP_EEPROM_HEADER_BIG
#define RAVE_SP_EEPROM_PAGE_SIZE 32U
/**
* struct rave_sp_eeprom_page - RAVE SP EEPROM page
*
* @type: Access type (see enum rave_sp_eeprom_access_type)
* @success: Success flag (Success = 1, Failure = 0)
* @data: Read data
*
* Note this structure corresponds to RSP_*_EEPROM payload from RAVE
* SP ICD
*/
struct rave_sp_eeprom_page {
u8 type;
u8 success;
u8 data[RAVE_SP_EEPROM_PAGE_SIZE];
} __packed;
/**
* struct rave_sp_eeprom - RAVE SP EEPROM device
*
* @sp: Pointer to parent RAVE SP device
* @mutex: Lock protecting access to EEPROM
* @address: EEPROM device address
* @header_size: Size of EEPROM command header for this device
* @dev: Pointer to corresponding struct device used for logging
*/
struct rave_sp_eeprom {
struct rave_sp *sp;
struct mutex mutex;
u8 address;
unsigned int header_size;
struct device *dev;
};
/**
* rave_sp_eeprom_io - Low-level part of EEPROM page access
*
* @eeprom: EEPROM device to write to
* @type: EEPROM access type (read or write)
* @idx: number of the EEPROM page
* @page: Data to write or buffer to store result (via page->data)
*
* This function does all of the low-level work required to perform a
* EEPROM access. This includes formatting correct command payload,
* sending it and checking received results.
*
* Returns zero in case of success or negative error code in
* case of failure.
*/
static int rave_sp_eeprom_io(struct rave_sp_eeprom *eeprom,
enum rave_sp_eeprom_access_type type,
u16 idx,
struct rave_sp_eeprom_page *page)
{
const bool is_write = type == RAVE_SP_EEPROM_WRITE;
const unsigned int data_size = is_write ? sizeof(page->data) : 0;
const unsigned int cmd_size = eeprom->header_size + data_size;
const unsigned int rsp_size =
is_write ? sizeof(*page) - sizeof(page->data) : sizeof(*page);
unsigned int offset = 0;
u8 cmd[RAVE_SP_EEPROM_HEADER_MAX + sizeof(page->data)];
int ret;
if (WARN_ON(cmd_size > sizeof(cmd)))
return -EINVAL;
cmd[offset++] = eeprom->address;
cmd[offset++] = 0;
cmd[offset++] = type;
cmd[offset++] = idx;
/*
* If there's still room in this command's header it means we
* are talkin to EEPROM that uses 16-bit page numbers and we
* have to specify index's MSB in payload as well.
*/
if (offset < eeprom->header_size)
cmd[offset++] = idx >> 8;
/*
* Copy our data to write to command buffer first. In case of
* a read data_size should be zero and memcpy would become a
* no-op
*/
memcpy(&cmd[offset], page->data, data_size);
ret = rave_sp_exec(eeprom->sp, cmd, cmd_size, page, rsp_size);
if (ret)
return ret;
if (page->type != type)
return -EPROTO;
if (!page->success)
return -EIO;
return 0;
}
/**
* rave_sp_eeprom_page_access - Access single EEPROM page
*
* @eeprom: EEPROM device to access
* @type: Access type to perform (read or write)
* @offset: Offset within EEPROM to access
* @data: Data buffer
* @data_len: Size of the data buffer
*
* This function performs a generic access to a single page or a
* portion thereof. Requested access MUST NOT cross the EEPROM page
* boundary.
*
* Returns zero in case of success or negative error code in
* case of failure.
*/
static int
rave_sp_eeprom_page_access(struct rave_sp_eeprom *eeprom,
enum rave_sp_eeprom_access_type type,
unsigned int offset, u8 *data,
size_t data_len)
{
const unsigned int page_offset = offset % RAVE_SP_EEPROM_PAGE_SIZE;
const unsigned int page_nr = offset / RAVE_SP_EEPROM_PAGE_SIZE;
struct rave_sp_eeprom_page page;
int ret;
/*
* This function will not work if data access we've been asked
* to do is crossing EEPROM page boundary. Normally this
* should never happen and getting here would indicate a bug
* in the code.
*/
if (WARN_ON(data_len > sizeof(page.data) - page_offset))
return -EINVAL;
if (type == RAVE_SP_EEPROM_WRITE) {
/*
* If doing a partial write we need to do a read first
* to fill the rest of the page with correct data.
*/
if (data_len < RAVE_SP_EEPROM_PAGE_SIZE) {
ret = rave_sp_eeprom_io(eeprom, RAVE_SP_EEPROM_READ,
page_nr, &page);
if (ret)
return ret;
}
memcpy(&page.data[page_offset], data, data_len);
}
ret = rave_sp_eeprom_io(eeprom, type, page_nr, &page);
if (ret)
return ret;
/*
* Since we receive the result of the read via 'page.data'
* buffer we need to copy that to 'data'
*/
if (type == RAVE_SP_EEPROM_READ)
memcpy(data, &page.data[page_offset], data_len);
return 0;
}
/**
* rave_sp_eeprom_access - Access EEPROM data
*
* @eeprom: EEPROM device to access
* @type: Access type to perform (read or write)
* @offset: Offset within EEPROM to access
* @data: Data buffer
* @data_len: Size of the data buffer
*
* This function performs a generic access (either read or write) at
* arbitrary offset (not necessary page aligned) of arbitrary length
* (is not constrained by EEPROM page size).
*
* Returns zero in case of success or negative error code in case of
* failure.
*/
static int rave_sp_eeprom_access(struct rave_sp_eeprom *eeprom,
enum rave_sp_eeprom_access_type type,
unsigned int offset, u8 *data,
unsigned int data_len)
{
unsigned int residue;
unsigned int chunk;
unsigned int head;
int ret;
mutex_lock(&eeprom->mutex);
head = offset % RAVE_SP_EEPROM_PAGE_SIZE;
residue = data_len;
do {
/*
* First iteration, if we are doing an access that is
* not 32-byte aligned, we need to access only data up
* to a page boundary to avoid corssing it in
* rave_sp_eeprom_page_access()
*/
if (unlikely(head)) {
chunk = RAVE_SP_EEPROM_PAGE_SIZE - head;
/*
* This can only happen once per
* rave_sp_eeprom_access() call, so we set
* head to zero to process all the other
* iterations normally.
*/
head = 0;
} else {
chunk = RAVE_SP_EEPROM_PAGE_SIZE;
}
/*
* We should never read more that 'residue' bytes
*/
chunk = min(chunk, residue);
ret = rave_sp_eeprom_page_access(eeprom, type, offset,
data, chunk);
if (ret)
goto out;
residue -= chunk;
offset += chunk;
data += chunk;
} while (residue);
out:
mutex_unlock(&eeprom->mutex);
return ret;
}
static int rave_sp_eeprom_reg_read(void *eeprom, unsigned int offset,
void *val, size_t bytes)
{
return rave_sp_eeprom_access(eeprom, RAVE_SP_EEPROM_READ,
offset, val, bytes);
}
static int rave_sp_eeprom_reg_write(void *eeprom, unsigned int offset,
void *val, size_t bytes)
{
return rave_sp_eeprom_access(eeprom, RAVE_SP_EEPROM_WRITE,
offset, val, bytes);
}
static int rave_sp_eeprom_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct rave_sp *sp = dev_get_drvdata(dev->parent);
struct device_node *np = dev->of_node;
struct nvmem_config config = { 0 };
struct rave_sp_eeprom *eeprom;
struct nvmem_device *nvmem;
u32 reg[2], size;
if (of_property_read_u32_array(np, "reg", reg, ARRAY_SIZE(reg))) {
dev_err(dev, "Failed to parse \"reg\" property\n");
return -EINVAL;
}
size = reg[1];
/*
* Per ICD, we have no more than 2 bytes to specify EEPROM
* page.
*/
if (size > U16_MAX * RAVE_SP_EEPROM_PAGE_SIZE) {
dev_err(dev, "Specified size is too big\n");
return -EINVAL;
}
eeprom = devm_kzalloc(dev, sizeof(*eeprom), GFP_KERNEL);
if (!eeprom)
return -ENOMEM;
eeprom->address = reg[0];
eeprom->sp = sp;
eeprom->dev = dev;
if (size > SZ_8K)
eeprom->header_size = RAVE_SP_EEPROM_HEADER_BIG;
else
eeprom->header_size = RAVE_SP_EEPROM_HEADER_SMALL;
mutex_init(&eeprom->mutex);
config.id = -1;
of_property_read_string(np, "zii,eeprom-name", &config.name);
config.priv = eeprom;
config.dev = dev;
config.add_legacy_fixed_of_cells = true;
config.size = size;
config.reg_read = rave_sp_eeprom_reg_read;
config.reg_write = rave_sp_eeprom_reg_write;
config.word_size = 1;
config.stride = 1;
nvmem = devm_nvmem_register(dev, &config);
return PTR_ERR_OR_ZERO(nvmem);
}
static const struct of_device_id rave_sp_eeprom_of_match[] = {
{ .compatible = "zii,rave-sp-eeprom" },
{}
};
MODULE_DEVICE_TABLE(of, rave_sp_eeprom_of_match);
static struct platform_driver rave_sp_eeprom_driver = {
.probe = rave_sp_eeprom_probe,
.driver = {
.name = KBUILD_MODNAME,
.of_match_table = rave_sp_eeprom_of_match,
},
};
module_platform_driver(rave_sp_eeprom_driver);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Andrey Vostrikov <andrey.vostrikov@cogentembedded.com>");
MODULE_AUTHOR("Nikita Yushchenko <nikita.yoush@cogentembedded.com>");
MODULE_AUTHOR("Andrey Smirnov <andrew.smirnov@gmail.com>");
MODULE_DESCRIPTION("RAVE SP EEPROM driver");