[PATCH 11/11] nvmem: imx-ocotp: add write support
From: Srinivas Kandagatla
Date: Fri Mar 31 2017 - 08:47:59 EST
From: Richard Leitner <richard.leitner@xxxxxxxxxxx>
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>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
---
.../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 bbde2e4..70d791b 100644
--- a/Documentation/devicetree/bindings/nvmem/imx-ocotp.txt
+++ b/Documentation/devicetree/bindings/nvmem/imx-ocotp.txt
@@ -14,10 +14,14 @@ 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 0bb8d0d..193ca8f 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[] = {
@@ -142,7 +346,9 @@ 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);
--
2.7.4