diff options
Diffstat (limited to 'drivers/nvmem/mxs-ocotp.c')
| -rw-r--r-- | drivers/nvmem/mxs-ocotp.c | 217 |
1 files changed, 217 insertions, 0 deletions
diff --git a/drivers/nvmem/mxs-ocotp.c b/drivers/nvmem/mxs-ocotp.c new file mode 100644 index 000000000..7018e2ef5 --- /dev/null +++ b/drivers/nvmem/mxs-ocotp.c @@ -0,0 +1,217 @@ +/* + * 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/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 int mxs_ocotp_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + const struct mxs_data *data; + struct mxs_ocotp *otp; + struct resource *res; + const struct of_device_id *match; + 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; + } + + data = match->data; + + ocotp_config.size = data->size; + ocotp_config.priv = otp; + 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"); |