Implement write routine for OCOTP controller found in i.MX6 SoC's. Furthermore add locking to the read function to prevent race conditions. The write routine code is based on the fsl_otp driver from Freescale. Signed-off-by: Richard Leitner <richard.leitner@xxxxxxxxxxx> --- .../devicetree/bindings/nvmem/imx-ocotp.txt | 4 + drivers/nvmem/imx-ocotp.c | 210 ++++++++++++++++++++- 2 files changed, 212 insertions(+), 2 deletions(-) diff --git a/Documentation/devicetree/bindings/nvmem/imx-ocotp.txt b/Documentation/devicetree/bindings/nvmem/imx-ocotp.txt index 966a72e..4b04356 100644 --- a/Documentation/devicetree/bindings/nvmem/imx-ocotp.txt +++ b/Documentation/devicetree/bindings/nvmem/imx-ocotp.txt @@ -13,10 +13,14 @@ Required properties: - reg: Should contain the register base and length. - clocks: Should contain a phandle pointing to the gated peripheral clock. +Optional properties: +- read-only: disable write access + Example: ocotp: ocotp@021bc000 { compatible = "fsl,imx6q-ocotp", "syscon"; reg = <0x021bc000 0x4000>; clocks = <&clks IMX6QDL_CLK_IIM>; + read-only; }; diff --git a/drivers/nvmem/imx-ocotp.c b/drivers/nvmem/imx-ocotp.c index e2b62b3..eb55b41 100644 --- a/drivers/nvmem/imx-ocotp.c +++ b/drivers/nvmem/imx-ocotp.c @@ -7,6 +7,9 @@ * Copyright (c) 2010 Baruch Siach <baruch@xxxxxxxxxx>, * Orex Computed Radiography * + * Write support based on the fsl_otp driver, + * Copyright (C) 2010-2013 Freescale Semiconductor, Inc + * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 * as published by the Free Software Foundation. @@ -24,6 +27,7 @@ #include <linux/of_device.h> #include <linux/platform_device.h> #include <linux/slab.h> +#include <linux/delay.h> #define IMX_OCOTP_OFFSET_B0W0 0x400 /* Offset from base address of the * OTP Bank0 Word0 @@ -31,20 +35,69 @@ #define IMX_OCOTP_OFFSET_PER_WORD 0x10 /* Offset between the start addr * of two consecutive OTP words. */ + #define IMX_OCOTP_ADDR_CTRL 0x0000 +#define IMX_OCOTP_ADDR_CTRL_SET 0x0004 #define IMX_OCOTP_ADDR_CTRL_CLR 0x0008 +#define IMX_OCOTP_ADDR_TIMING 0x0010 +#define IMX_OCOTP_ADDR_DATA 0x0020 +#define IMX_OCOTP_BM_CTRL_ADDR 0x0000007F +#define IMX_OCOTP_BM_CTRL_BUSY 0x00000100 #define IMX_OCOTP_BM_CTRL_ERROR 0x00000200 +#define IMX_OCOTP_BM_CTRL_REL_SHADOWS 0x00000400 +#define DEF_RELAX 20 /* > 16.5ns */ +#define IMX_OCOTP_WR_UNLOCK 0x3E770000 #define IMX_OCOTP_READ_LOCKED_VAL 0xBADABADA +static DEFINE_MUTEX(ocotp_mutex); + struct ocotp_priv { struct device *dev; struct clk *clk; void __iomem *base; unsigned int nregs; + struct nvmem_config *config; }; +static int imx_ocotp_wait_for_busy(void __iomem *base, u32 flags) +{ + int count; + u32 c, mask; + + mask = IMX_OCOTP_BM_CTRL_BUSY | IMX_OCOTP_BM_CTRL_ERROR | flags; + + for (count = 10000; count >= 0; count--) { + c = readl(base + IMX_OCOTP_ADDR_CTRL); + if (!(c & mask)) + break; + cpu_relax(); + } + + if (count < 0) { + /* HW_OCOTP_CTRL[ERROR] will be set under the following + * conditions: + * - A write is performed to a shadow register during a shadow + * reload (essentially, while HW_OCOTP_CTRL[RELOAD_SHADOWS] is + * set. In addition, the contents of the shadow register shall + * not be updated. + * - A write is performed to a shadow register which has been + * locked. + * - A read is performed to from a shadow register which has + * been read locked. + * - A program is performed to a fuse word which has been locked + * - A read is performed to from a fuse word which has been read + * locked. + */ + if (c & IMX_OCOTP_BM_CTRL_ERROR) + return -EPERM; + return -ETIMEDOUT; + } + + return 0; +} + static void imx_ocotp_clr_err_if_set(void __iomem *base) { u32 c; @@ -71,12 +124,21 @@ static int imx_ocotp_read(void *context, unsigned int offset, if (count > (priv->nregs - index)) count = priv->nregs - index; + mutex_lock(&ocotp_mutex); + ret = clk_prepare_enable(priv->clk); if (ret < 0) { + mutex_unlock(&ocotp_mutex); dev_err(priv->dev, "failed to prepare/enable ocotp clk\n"); return ret; } + ret = imx_ocotp_wait_for_busy(priv->base, 0); + if (ret < 0) { + dev_err(priv->dev, "timeout during read setup\n"); + goto read_end; + } + for (i = index; i < (index + count); i++) { *buf++ = readl(priv->base + IMX_OCOTP_OFFSET_B0W0 + i * IMX_OCOTP_OFFSET_PER_WORD); @@ -90,18 +152,160 @@ static int imx_ocotp_read(void *context, unsigned int offset, if (*(buf - 1) == IMX_OCOTP_READ_LOCKED_VAL) imx_ocotp_clr_err_if_set(priv->base); } + ret = 0; +read_end: clk_disable_unprepare(priv->clk); - return 0; + mutex_unlock(&ocotp_mutex); + return ret; +} + +static int imx_ocotp_write(void *context, unsigned int offset, void *val, + size_t bytes) +{ + struct ocotp_priv *priv = context; + u32 *buf = val; + int ret; + + unsigned long clk_rate = 0; + unsigned long strobe_read, relax, strobe_prog; + u32 timing = 0; + u32 ctrl; + u8 waddr; + + /* allow only writing one complete OTP word at a time */ + if ((bytes != priv->config->word_size) || + (offset % priv->config->word_size)) + return -EINVAL; + + mutex_lock(&ocotp_mutex); + + ret = clk_prepare_enable(priv->clk); + if (ret < 0) { + mutex_unlock(&ocotp_mutex); + dev_err(priv->dev, "failed to prepare/enable ocotp clk\n"); + return ret; + } + + /* 47.3.1.3.1 + * Program HW_OCOTP_TIMING[STROBE_PROG] and HW_OCOTP_TIMING[RELAX] + * fields with timing values to match the current frequency of the + * ipg_clk. OTP writes will work at maximum bus frequencies as long + * as the HW_OCOTP_TIMING parameters are set correctly. + */ + clk_rate = clk_get_rate(priv->clk); + + relax = clk_rate / (1000000000 / DEF_RELAX) - 1; + strobe_prog = clk_rate / (1000000000 / 10000) + 2 * (DEF_RELAX + 1) - 1; + strobe_read = clk_rate / (1000000000 / 40) + 2 * (DEF_RELAX + 1) - 1; + + timing = strobe_prog & 0x00000FFF; + timing |= (relax << 12) & 0x0000F000; + timing |= (strobe_read << 16) & 0x003F0000; + + writel(timing, priv->base + IMX_OCOTP_ADDR_TIMING); + + /* 47.3.1.3.2 + * Check that HW_OCOTP_CTRL[BUSY] and HW_OCOTP_CTRL[ERROR] are clear. + * Overlapped accesses are not supported by the controller. Any pending + * write or reload must be completed before a write access can be + * requested. + */ + ret = imx_ocotp_wait_for_busy(priv->base, 0); + if (ret < 0) { + dev_err(priv->dev, "timeout during timing setup\n"); + goto write_end; + } + + /* 47.3.1.3.3 + * Write the requested address to HW_OCOTP_CTRL[ADDR] and program the + * unlock code into HW_OCOTP_CTRL[WR_UNLOCK]. This must be programmed + * for each write access. The lock code is documented in the register + * description. Both the unlock code and address can be written in the + * same operation. + */ + /* OTP write/read address specifies one of 128 word address locations */ + waddr = offset / 4; + + ctrl = readl(priv->base + IMX_OCOTP_ADDR_CTRL); + ctrl &= ~IMX_OCOTP_BM_CTRL_ADDR; + ctrl |= waddr & IMX_OCOTP_BM_CTRL_ADDR; + ctrl |= IMX_OCOTP_WR_UNLOCK; + + writel(ctrl, priv->base + IMX_OCOTP_ADDR_CTRL); + + /* 47.3.1.3.4 + * Write the data to the HW_OCOTP_DATA register. This will automatically + * set HW_OCOTP_CTRL[BUSY] and clear HW_OCOTP_CTRL[WR_UNLOCK]. To + * protect programming same OTP bit twice, before program OCOTP will + * automatically read fuse value in OTP and use read value to mask + * program data. The controller will use masked program data to program + * a 32-bit word in the OTP per the address in HW_OCOTP_CTRL[ADDR]. Bit + * fields with 1's will result in that OTP bit being programmed. Bit + * fields with 0's will be ignored. At the same time that the write is + * accepted, the controller makes an internal copy of + * HW_OCOTP_CTRL[ADDR] which cannot be updated until the next write + * sequence is initiated. This copy guarantees that erroneous writes to + * HW_OCOTP_CTRL[ADDR] will not affect an active write operation. It + * should also be noted that during the programming HW_OCOTP_DATA will + * shift right (with zero fill). This shifting is required to program + * the OTP serially. During the write operation, HW_OCOTP_DATA cannot be + * modified. + */ + writel(*buf, priv->base + IMX_OCOTP_ADDR_DATA); + + /* 47.4.1.4.5 + * Once complete, the controller will clear BUSY. A write request to a + * protected or locked region will result in no OTP access and no + * setting of HW_OCOTP_CTRL[BUSY]. In addition HW_OCOTP_CTRL[ERROR] will + * be set. It must be cleared by software before any new write access + * can be issued. + */ + ret = imx_ocotp_wait_for_busy(priv->base, 0); + if (ret < 0) { + if (ret == -EPERM) { + dev_err(priv->dev, "failed write to locked region"); + imx_ocotp_clr_err_if_set(priv->base); + } else { + dev_err(priv->dev, "timeout during data write\n"); + } + goto write_end; + } + + /* 47.3.1.4 + * Write Postamble: Due to internal electrical characteristics of the + * OTP during writes, all OTP operations following a write must be + * separated by 2 us after the clearing of HW_OCOTP_CTRL_BUSY following + * the write. + */ + udelay(2); + + /* reload all shadow registers */ + writel(IMX_OCOTP_BM_CTRL_REL_SHADOWS, + priv->base + IMX_OCOTP_ADDR_CTRL_SET); + ret = imx_ocotp_wait_for_busy(priv->base, + IMX_OCOTP_BM_CTRL_REL_SHADOWS); + if (ret < 0) { + dev_err(priv->dev, "timeout during shadow register reload\n"); + goto write_end; + } + +write_end: + clk_disable_unprepare(priv->clk); + mutex_unlock(&ocotp_mutex); + if (ret < 0) + return ret; + return bytes; } static struct nvmem_config imx_ocotp_nvmem_config = { .name = "imx-ocotp", - .read_only = true, + .read_only = false, .word_size = 4, .stride = 4, .owner = THIS_MODULE, .reg_read = imx_ocotp_read, + .reg_write = imx_ocotp_write, }; static const struct of_device_id imx_ocotp_dt_ids[] = { @@ -139,7 +343,9 @@ static int imx_ocotp_probe(struct platform_device *pdev) imx_ocotp_nvmem_config.size = 4 * priv->nregs; imx_ocotp_nvmem_config.dev = dev; imx_ocotp_nvmem_config.priv = priv; + priv->config = &imx_ocotp_nvmem_config; nvmem = nvmem_register(&imx_ocotp_nvmem_config); + if (IS_ERR(nvmem)) return PTR_ERR(nvmem); -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html