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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Freescale MXS On-Chip OTP driver
*
* Copyright (C) 2015 Stefan Wahren <stefan.wahren@i2se.com>
*
* Based on the driver from Huang Shijie and Christoph G. Baumann
*/
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/nvmem-provider.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/slab.h>
#include <linux/stmp_device.h>
/* OCOTP registers and bits */
#define BM_OCOTP_CTRL_RD_BANK_OPEN BIT(12)
#define BM_OCOTP_CTRL_ERROR BIT(9)
#define BM_OCOTP_CTRL_BUSY BIT(8)
#define OCOTP_TIMEOUT 10000
#define OCOTP_DATA_OFFSET 0x20
struct mxs_ocotp {
struct clk *clk;
void __iomem *base;
struct nvmem_device *nvmem;
};
static int mxs_ocotp_wait(struct mxs_ocotp *otp)
{
int timeout = OCOTP_TIMEOUT;
unsigned int status = 0;
while (timeout--) {
status = readl(otp->base);
if (!(status & (BM_OCOTP_CTRL_BUSY | BM_OCOTP_CTRL_ERROR)))
break;
cpu_relax();
}
if (status & BM_OCOTP_CTRL_BUSY)
return -EBUSY;
else if (status & BM_OCOTP_CTRL_ERROR)
return -EIO;
return 0;
}
static int mxs_ocotp_read(void *context, unsigned int offset,
void *val, size_t bytes)
{
struct mxs_ocotp *otp = context;
u32 *buf = val;
int ret;
ret = clk_enable(otp->clk);
if (ret)
return ret;
writel(BM_OCOTP_CTRL_ERROR, otp->base + STMP_OFFSET_REG_CLR);
ret = mxs_ocotp_wait(otp);
if (ret)
goto disable_clk;
/* open OCOTP banks for read */
writel(BM_OCOTP_CTRL_RD_BANK_OPEN, otp->base + STMP_OFFSET_REG_SET);
/* approximately wait 33 hclk cycles */
udelay(1);
ret = mxs_ocotp_wait(otp);
if (ret)
goto close_banks;
while (bytes) {
if ((offset < OCOTP_DATA_OFFSET) || (offset % 16)) {
/* fill up non-data register */
*buf++ = 0;
} else {
*buf++ = readl(otp->base + offset);
}
bytes -= 4;
offset += 4;
}
close_banks:
/* close banks for power saving */
writel(BM_OCOTP_CTRL_RD_BANK_OPEN, otp->base + STMP_OFFSET_REG_CLR);
disable_clk:
clk_disable(otp->clk);
return ret;
}
static struct nvmem_config ocotp_config = {
.name = "mxs-ocotp",
.stride = 16,
.word_size = 4,
.reg_read = mxs_ocotp_read,
};
struct mxs_data {
int size;
};
static const struct mxs_data imx23_data = {
.size = 0x220,
};
static const struct mxs_data imx28_data = {
.size = 0x2a0,
};
static const struct of_device_id mxs_ocotp_match[] = {
{ .compatible = "fsl,imx23-ocotp", .data = &imx23_data },
{ .compatible = "fsl,imx28-ocotp", .data = &imx28_data },
{ /* sentinel */},
};
MODULE_DEVICE_TABLE(of, mxs_ocotp_match);
static void mxs_ocotp_action(void *data)
{
clk_unprepare(data);
}
static int mxs_ocotp_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
const struct mxs_data *data;
struct mxs_ocotp *otp;
int ret;
data = device_get_match_data(dev);
if (!data)
return -EINVAL;
otp = devm_kzalloc(dev, sizeof(*otp), GFP_KERNEL);
if (!otp)
return -ENOMEM;
otp->base = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(otp->base))
return PTR_ERR(otp->base);
otp->clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(otp->clk))
return PTR_ERR(otp->clk);
ret = clk_prepare(otp->clk);
if (ret < 0) {
dev_err(dev, "failed to prepare clk: %d\n", ret);
return ret;
}
ret = devm_add_action_or_reset(&pdev->dev, mxs_ocotp_action, otp->clk);
if (ret)
return ret;
ocotp_config.size = data->size;
ocotp_config.priv = otp;
ocotp_config.dev = dev;
otp->nvmem = devm_nvmem_register(dev, &ocotp_config);
if (IS_ERR(otp->nvmem))
return PTR_ERR(otp->nvmem);
platform_set_drvdata(pdev, otp);
return 0;
}
static struct platform_driver mxs_ocotp_driver = {
.probe = mxs_ocotp_probe,
.driver = {
.name = "mxs-ocotp",
.of_match_table = mxs_ocotp_match,
},
};
module_platform_driver(mxs_ocotp_driver);
MODULE_AUTHOR("Stefan Wahren <wahrenst@gmx.net");
MODULE_DESCRIPTION("driver for OCOTP in i.MX23/i.MX28");
MODULE_LICENSE("GPL v2");
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