// 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 <[email protected]>");
MODULE_AUTHOR("Nikita Yushchenko <[email protected]>");
MODULE_AUTHOR("Andrey Smirnov <[email protected]>");
MODULE_DESCRIPTION("RAVE SP EEPROM driver");
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