linux/drivers/nvmem/mxs-ocotp.c
Stefan Wahren c01e9a11ab nvmem: add driver for ocotp in i.MX23 and i.MX28
This patch brings read-only support for the On-Chip OTP cells
in the i.MX23 and i.MX28 processor. The driver implements the
new NVMEM provider API.

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Reviewed-by: Marek Vasut <marex@denx.de>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-10-04 12:06:13 +01:00

258 lines
5.9 KiB
C

/*
* 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
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
*/
#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_device.h>
#include <linux/platform_device.h>
#include <linux/regmap.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, const void *reg, size_t reg_size,
void *val, size_t val_size)
{
struct mxs_ocotp *otp = context;
unsigned int offset = *(u32 *)reg;
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 (val_size) {
if ((offset < OCOTP_DATA_OFFSET) || (offset % 16)) {
/* fill up non-data register */
*buf = 0;
} else {
*buf = readl(otp->base + offset);
}
buf++;
val_size--;
offset += reg_size;
}
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 int mxs_ocotp_write(void *context, const void *data, size_t count)
{
/* We don't want to support writing */
return 0;
}
static bool mxs_ocotp_writeable_reg(struct device *dev, unsigned int reg)
{
return false;
}
static struct nvmem_config ocotp_config = {
.name = "mxs-ocotp",
.owner = THIS_MODULE,
};
static const struct regmap_range imx23_ranges[] = {
regmap_reg_range(OCOTP_DATA_OFFSET, 0x210),
};
static const struct regmap_access_table imx23_access = {
.yes_ranges = imx23_ranges,
.n_yes_ranges = ARRAY_SIZE(imx23_ranges),
};
static const struct regmap_range imx28_ranges[] = {
regmap_reg_range(OCOTP_DATA_OFFSET, 0x290),
};
static const struct regmap_access_table imx28_access = {
.yes_ranges = imx28_ranges,
.n_yes_ranges = ARRAY_SIZE(imx28_ranges),
};
static struct regmap_bus mxs_ocotp_bus = {
.read = mxs_ocotp_read,
.write = mxs_ocotp_write, /* make regmap_init() happy */
.reg_format_endian_default = REGMAP_ENDIAN_NATIVE,
.val_format_endian_default = REGMAP_ENDIAN_NATIVE,
};
static struct regmap_config mxs_ocotp_config = {
.reg_bits = 32,
.val_bits = 32,
.reg_stride = 16,
.writeable_reg = mxs_ocotp_writeable_reg,
};
static const struct of_device_id mxs_ocotp_match[] = {
{ .compatible = "fsl,imx23-ocotp", .data = &imx23_access },
{ .compatible = "fsl,imx28-ocotp", .data = &imx28_access },
{ /* sentinel */},
};
MODULE_DEVICE_TABLE(of, mxs_ocotp_match);
static int mxs_ocotp_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct mxs_ocotp *otp;
struct resource *res;
const struct of_device_id *match;
struct regmap *regmap;
const struct regmap_access_table *access;
int ret;
match = of_match_device(dev->driver->of_match_table, dev);
if (!match || !match->data)
return -EINVAL;
otp = devm_kzalloc(dev, sizeof(*otp), GFP_KERNEL);
if (!otp)
return -ENOMEM;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
otp->base = devm_ioremap_resource(dev, res);
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;
}
access = match->data;
mxs_ocotp_config.rd_table = access;
mxs_ocotp_config.max_register = access->yes_ranges[0].range_max;
regmap = devm_regmap_init(dev, &mxs_ocotp_bus, otp, &mxs_ocotp_config);
if (IS_ERR(regmap)) {
dev_err(dev, "regmap init failed\n");
ret = PTR_ERR(regmap);
goto err_clk;
}
ocotp_config.dev = dev;
otp->nvmem = nvmem_register(&ocotp_config);
if (IS_ERR(otp->nvmem)) {
ret = PTR_ERR(otp->nvmem);
goto err_clk;
}
platform_set_drvdata(pdev, otp);
return 0;
err_clk:
clk_unprepare(otp->clk);
return ret;
}
static int mxs_ocotp_remove(struct platform_device *pdev)
{
struct mxs_ocotp *otp = platform_get_drvdata(pdev);
clk_unprepare(otp->clk);
return nvmem_unregister(otp->nvmem);
}
static struct platform_driver mxs_ocotp_driver = {
.probe = mxs_ocotp_probe,
.remove = mxs_ocotp_remove,
.driver = {
.name = "mxs-ocotp",
.of_match_table = mxs_ocotp_match,
},
};
module_platform_driver(mxs_ocotp_driver);
MODULE_AUTHOR("Stefan Wahren <stefan.wahren@i2se.com>");
MODULE_DESCRIPTION("driver for OCOTP in i.MX23/i.MX28");
MODULE_LICENSE("GPL v2");