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drivers: syscon: Add generic syscon API

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A syscon device is a device managing a memory region containing a set of
registers that are not cohesive enough to represent as any specific type
of device. We need a driver for that because several other drivers could
use the same region at the same time and we need to io-map the region at
boot for MMU enabled platforms.

Signed-off-by: Carlo Caione <ccaione@baylibre.com>
This commit is contained in:
Carlo Caione 2021-06-03 11:03:48 +02:00 • committed by Christopher Friedt
commit bc30598456
8 changed files with 249 additions and 0 deletions
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117
drivers/syscon/syscon.c Normal file
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/*
* Copyright (c) Carlo Caione <ccaione@baylibre.com>
*
* SPDX-License-Identifier: Apache-2.0
*/
#define DT_DRV_COMPAT syscon
#include <sys/util.h>
#include <device.h>
#include <init.h>
#include <drivers/syscon.h>
static const struct device *syscon_dev;
struct syscon_generic_config {
DEVICE_MMIO_ROM;
};
static struct syscon_generic_config syscon_generic_config_0 = {
DEVICE_MMIO_ROM_INIT(DT_DRV_INST(0)),
};
struct syscon_generic_data {
DEVICE_MMIO_RAM;
size_t size;
};
static struct syscon_generic_data syscon_generic_data_0;
uintptr_t syscon_generic_get_base(void)
{
if (!syscon_dev) {
return -ENODEV;
}
return DEVICE_MMIO_GET(syscon_dev);
}
static int sanitize_reg(uint16_t *reg, size_t reg_size)
{
/* Avoid unaligned readings */
*reg = ROUND_DOWN(*reg, sizeof(uint32_t));
/* Check for out-of-bounds readings */
if (*reg >= reg_size) {
return -EINVAL;
}
return 0;
}
int syscon_generic_read_reg(uint16_t reg, uint32_t *val)
{
struct syscon_generic_data *data;
uintptr_t base_address;
if (!syscon_dev) {
return -ENODEV;
}
data = syscon_dev->data;
if (!val) {
return -EINVAL;
}
if (sanitize_reg(&reg, data->size)) {
return -EINVAL;
}
base_address = DEVICE_MMIO_GET(syscon_dev);
*val = sys_read32(base_address + reg);
return 0;
}
int syscon_generic_write_reg(uint16_t reg, uint32_t val)
{
struct syscon_generic_data *data;
uintptr_t base_address;
if (!syscon_dev) {
return -ENODEV;
}
data = syscon_dev->data;
if (sanitize_reg(&reg, data->size)) {
return -EINVAL;
}
base_address = DEVICE_MMIO_GET(syscon_dev);
sys_write32(val, (base_address + reg));
return 0;
}
int syscon_generic_init(const struct device *dev)
{
struct syscon_generic_data *data = dev->data;
syscon_dev = dev;
DEVICE_MMIO_MAP(syscon_dev, K_MEM_CACHE_NONE);
data->size = DT_REG_SIZE(DT_DRV_INST(0));
return 0;
}
DEVICE_DT_INST_DEFINE(0, syscon_generic_init, NULL, &syscon_generic_data_0,
&syscon_generic_config_0, PRE_KERNEL_1,
CONFIG_SYSCON_GENERIC_INIT_PRIORITY_DEVICE, NULL);