ARM: mxs: add ocotp read function

Signed-off-by: Shawn Guo <shawn.guo@freescale.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 90 insertions, 0 deletions

diff --git a/arch/arm/mach-mxs/ocotp.c b/arch/arm/mach-mxs/ocotp.c
new file mode 100644
index 000000000000..65157a35dbba
--- /dev/null
+++ b/arch/arm/mach-mxs/ocotp.c
@@ -0,0 +1,90 @@
+/*
+ * Copyright 2010 Freescale Semiconductor, Inc. All Rights Reserved.
+ *
+ * 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/delay.h>
+#include <linux/err.h>
+#include <linux/mutex.h>
+
+#include <mach/mxs.h>
+
+#define OCOTP_WORD_OFFSET               0x20
+#define OCOTP_WORD_COUNT                0x20
+
+#define BM_OCOTP_CTRL_BUSY              (1 << 8)
+#define BM_OCOTP_CTRL_ERROR             (1 << 9)
+#define BM_OCOTP_CTRL_RD_BANK_OPEN      (1 << 12)
+
+static DEFINE_MUTEX(ocotp_mutex);
+static u32 ocotp_words[OCOTP_WORD_COUNT];
+
+const u32 *mxs_get_ocotp(void)
+{
+        void __iomem *ocotp_base = MXS_IO_ADDRESS(MXS_OCOTP_BASE_ADDR);
+        int timeout = 0x400;
+        size_t i;
+        static int once = 0;
+
+        if (once)
+                return ocotp_words;
+
+        mutex_lock(&ocotp_mutex);
+
+        /*
+         * clk_enable(hbus_clk) for ocotp can be skipped
+         * as it must be on when system is running.
+         */
+
+        /* try to clear ERROR bit */
+        __mxs_clrl(BM_OCOTP_CTRL_ERROR, ocotp_base);
+
+        /* check both BUSY and ERROR cleared */
+        while ((__raw_readl(ocotp_base) &
+                (BM_OCOTP_CTRL_BUSY | BM_OCOTP_CTRL_ERROR)) && --timeout)
+                cpu_relax();
+
+        if (unlikely(!timeout))
+                goto error_unlock;
+
+        /* open OCOTP banks for read */
+        __mxs_setl(BM_OCOTP_CTRL_RD_BANK_OPEN, ocotp_base);
+
+        /* approximately wait 32 hclk cycles */
+        udelay(1);
+
+        /* poll BUSY bit becoming cleared */
+        timeout = 0x400;
+        while ((__raw_readl(ocotp_base) & BM_OCOTP_CTRL_BUSY) && --timeout)
+                cpu_relax();
+
+        if (unlikely(!timeout))
+                goto error_unlock;
+
+        for (i = 0; i < OCOTP_WORD_COUNT; i++)
+                ocotp_words[i] = __raw_readl(ocotp_base + OCOTP_WORD_OFFSET +
+                                                i * 0x10);
+
+        /* close banks for power saving */
+        __mxs_clrl(BM_OCOTP_CTRL_RD_BANK_OPEN, ocotp_base);
+
+        once = 1;
+
+        mutex_unlock(&ocotp_mutex);
+
+        return ocotp_words;
+
+error_unlock:
+        mutex_unlock(&ocotp_mutex);
+        pr_err("%s: timeout in reading OCOTP\n", __func__);
+        return NULL;
+}