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// SPDX-License-Identifier: GPL-2.0
/*
* LiteX SoC Controller Driver
*
* Copyright (C) 2020 Antmicro <www.antmicro.com>
*
*/
#include <linux/litex.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/printk.h>
#include <linux/module.h>
#include <linux/io.h>
#include <linux/reboot.h>
/* reset register located at the base address */
#define RESET_REG_OFF 0x00
#define RESET_REG_VALUE 0x00000001
#define SCRATCH_REG_OFF 0x04
#define SCRATCH_REG_VALUE 0x12345678
#define SCRATCH_TEST_VALUE 0xdeadbeef
/*
* Check LiteX CSR read/write access
*
* This function reads and writes a scratch register in order to verify if CSR
* access works.
*
* In case any problems are detected, the driver should panic.
*
* Access to the LiteX CSR is, by design, done in CPU native endianness.
* The driver should not dynamically configure access functions when
* the endianness mismatch is detected. Such situation indicates problems in
* the soft SoC design and should be solved at the LiteX generator level,
* not in the software.
*/
static int litex_check_csr_access(void __iomem *reg_addr)
{
unsigned long reg;
reg = litex_read32(reg_addr + SCRATCH_REG_OFF);
if (reg != SCRATCH_REG_VALUE) {
panic("Scratch register read error - the system is probably broken! Expected: 0x%x but got: 0x%lx",
SCRATCH_REG_VALUE, reg);
return -EINVAL;
}
litex_write32(reg_addr + SCRATCH_REG_OFF, SCRATCH_TEST_VALUE);
reg = litex_read32(reg_addr + SCRATCH_REG_OFF);
if (reg != SCRATCH_TEST_VALUE) {
panic("Scratch register write error - the system is probably broken! Expected: 0x%x but got: 0x%lx",
SCRATCH_TEST_VALUE, reg);
return -EINVAL;
}
/* restore original value of the SCRATCH register */
litex_write32(reg_addr + SCRATCH_REG_OFF, SCRATCH_REG_VALUE);
pr_info("LiteX SoC Controller driver initialized");
return 0;
}
struct litex_soc_ctrl_device {
void __iomem *base;
struct notifier_block reset_nb;
};
static int litex_reset_handler(struct notifier_block *this, unsigned long mode,
void *cmd)
{
struct litex_soc_ctrl_device *soc_ctrl_dev =
container_of(this, struct litex_soc_ctrl_device, reset_nb);
litex_write32(soc_ctrl_dev->base + RESET_REG_OFF, RESET_REG_VALUE);
return NOTIFY_DONE;
}
static const struct of_device_id litex_soc_ctrl_of_match[] = {
{.compatible = "litex,soc-controller"},
{},
};
MODULE_DEVICE_TABLE(of, litex_soc_ctrl_of_match);
static int litex_soc_ctrl_probe(struct platform_device *pdev)
{
struct litex_soc_ctrl_device *soc_ctrl_dev;
int error;
soc_ctrl_dev = devm_kzalloc(&pdev->dev, sizeof(*soc_ctrl_dev), GFP_KERNEL);
if (!soc_ctrl_dev)
return -ENOMEM;
soc_ctrl_dev->base = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(soc_ctrl_dev->base))
return PTR_ERR(soc_ctrl_dev->base);
error = litex_check_csr_access(soc_ctrl_dev->base);
if (error)
return error;
platform_set_drvdata(pdev, soc_ctrl_dev);
soc_ctrl_dev->reset_nb.notifier_call = litex_reset_handler;
soc_ctrl_dev->reset_nb.priority = 128;
error = register_restart_handler(&soc_ctrl_dev->reset_nb);
if (error) {
dev_warn(&pdev->dev, "cannot register restart handler: %d\n",
error);
}
return 0;
}
static void litex_soc_ctrl_remove(struct platform_device *pdev)
{
struct litex_soc_ctrl_device *soc_ctrl_dev = platform_get_drvdata(pdev);
unregister_restart_handler(&soc_ctrl_dev->reset_nb);
}
static struct platform_driver litex_soc_ctrl_driver = {
.driver = {
.name = "litex-soc-controller",
.of_match_table = litex_soc_ctrl_of_match,
},
.probe = litex_soc_ctrl_probe,
.remove_new = litex_soc_ctrl_remove,
};
module_platform_driver(litex_soc_ctrl_driver);
MODULE_DESCRIPTION("LiteX SoC Controller driver");
MODULE_AUTHOR("Antmicro <www.antmicro.com>");
MODULE_LICENSE("GPL v2");
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