[meta-freescale] [PATCH 1/1] arm: imx: fsl_otp: make fuses (OTP memory) read-only

[Alexander Holler]

Nothing in userspace should be able to kill the HW.
Not even just as root and for sure not that easy.

For obvious reason, I haven't tested this patch thoroughly.

Reported-by: Jon Nettleton <jon.nettleton at gmail.com>
Signed-off-by: Alexander Holler <holler at ahsoftware.de>
---
 drivers/char/fsl_otp.c | 57 +-------------------------------------------------
 1 file changed, 1 insertion(+), 56 deletions(-)

diff --git a/drivers/char/fsl_otp.c b/drivers/char/fsl_otp.c
index face297..d9d1c59 100644
--- a/drivers/char/fsl_otp.c
+++ b/drivers/char/fsl_otp.c
@@ -151,60 +151,6 @@ out:
 	return ret ? 0 : sprintf(buf, "0x%x\n", value);
 }
 
-static int otp_write_bits(int addr, u32 data, u32 magic)
-{
-	u32 c; /* for control register */
-
-	/* init the control register */
-	c = __raw_readl(otp_base + HW_OCOTP_CTRL);
-	c &= ~BM_OCOTP_CTRL_ADDR;
-	c |= BF(addr, OCOTP_CTRL_ADDR);
-	c |= BF(magic, OCOTP_CTRL_WR_UNLOCK);
-	__raw_writel(c, otp_base + HW_OCOTP_CTRL);
-
-	/* init the data register */
-	__raw_writel(data, otp_base + HW_OCOTP_DATA);
-	otp_wait_busy(0);
-
-	mdelay(2); /* Write Postamble */
-
-	return 0;
-}
-
-static ssize_t fsl_otp_store(struct kobject *kobj, struct kobj_attribute *attr,
-			     const char *buf, size_t count)
-{
-	unsigned int index = attr - otp_kattr;
-	u32 value;
-	int ret;
-
-	sscanf(buf, "0x%x", &value);
-
-	ret = clk_prepare_enable(otp_clk);
-	if (ret)
-		return 0;
-
-	mutex_lock(&otp_mutex);
-
-	set_otp_timing();
-	ret = otp_wait_busy(0);
-	if (ret)
-		goto out;
-
-	otp_write_bits(index, value, 0x3e77);
-
-	/* Reload all the shadow registers */
-	__raw_writel(BM_OCOTP_CTRL_RELOAD_SHADOWS,
-		     otp_base + HW_OCOTP_CTRL_SET);
-	udelay(1);
-	otp_wait_busy(BM_OCOTP_CTRL_RELOAD_SHADOWS);
-
-out:
-	mutex_unlock(&otp_mutex);
-	clk_disable_unprepare(otp_clk);
-	return ret ? 0 : count;
-}
-
 static int fsl_otp_probe(struct platform_device *pdev)
 {
 	struct resource *res;
@@ -244,9 +190,8 @@ static int fsl_otp_probe(struct platform_device *pdev)
 	for (i = 0; i < num; i++) {
 		sysfs_attr_init(&otp_kattr[i].attr);
 		otp_kattr[i].attr.name = desc[i];
-		otp_kattr[i].attr.mode = 0600;
+		otp_kattr[i].attr.mode = 0400;
 		otp_kattr[i].show = fsl_otp_show;
-		otp_kattr[i].store = fsl_otp_store;
 		attrs[i] = &otp_kattr[i].attr;
 	}
 	otp_attr_group->attrs = attrs;
-- 
1.8.3.1