Hello Sascha,
On Wed, Jan 12, 2011 at 03:50:36PM +0100, Sascha Hauer wrote:
On Wed, Jan 12, 2011 at 02:47:12PM +0800, Shawn Guo wrote:
quoted
On Tue, Jan 11, 2011 at 02:31:37PM +0100, Sascha Hauer wrote:
quoted
On Thu, Jan 06, 2011 at 03:13:16PM +0800, Shawn Guo wrote:
quoted
Signed-off-by: Shawn Guo <redacted>
---
Changes for v4:
- Call cpu_relax() during polling
Changes for v2:
- Add mutex locking for mxs_read_ocotp()
- Use type size_t for count and i
- Add comment for clk_enable/disable skipping
- Add ERROR bit clearing and polling step
arch/arm/mach-mxs/Makefile | 2 +-
arch/arm/mach-mxs/include/mach/common.h | 1 +
arch/arm/mach-mxs/ocotp.c | 79 +++++++++++++++++++++++++++++++
3 files changed, 81 insertions(+), 1 deletions(-)
create mode 100644 arch/arm/mach-mxs/ocotp.c
diff --git a/arch/arm/mach-mxs/Makefile b/arch/arm/mach-mxs/Makefile
index 39d3f9c..f23ebbd 100644
--- a/arch/arm/mach-mxs/Makefile
+++ b/arch/arm/mach-mxs/Makefile
@@ -1,5 +1,5 @@
# Common support
-obj-y := clock.o devices.o gpio.o icoll.o iomux.o system.o timer.o
+obj-y := clock.o devices.o gpio.o icoll.o iomux.o ocotp.o system.o timer.o
obj-$(CONFIG_SOC_IMX23) += clock-mx23.o mm-mx23.o
obj-$(CONFIG_SOC_IMX28) += clock-mx28.o mm-mx28.o
diff --git a/arch/arm/mach-mxs/include/mach/common.h b/arch/arm/mach-mxs/include/mach/common.h
index 59133eb..cf02552 100644
--- a/arch/arm/mach-mxs/include/mach/common.h
+++ b/arch/arm/mach-mxs/include/mach/common.h
@@ -13,6 +13,7 @@
struct clk;
+extern int mxs_read_ocotp(int offset, int count, u32 *values);
extern int mxs_reset_block(void __iomem *);
extern void mxs_timer_init(struct clk *, int);
diff --git a/arch/arm/mach-mxs/ocotp.c b/arch/arm/mach-mxs/ocotp.c
new file mode 100644
index 0000000..e2d39aa
--- /dev/null
+++ b/arch/arm/mach-mxs/ocotp.c
@@ -0,0 +1,79 @@
+/*
+ * 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 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);
+
+int mxs_read_ocotp(unsigned offset, size_t count, u32 *values)
+{
+ void __iomem *ocotp_base = MXS_IO_ADDRESS(MXS_OCOTP_BASE_ADDR);
+ int timeout = 0x400;
+ size_t i;
+
+ 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);
This operation does not try to clear the error bit but actually clears
it...
quoted
+
+ /* check both BUSY and ERROR cleared */
+ while ((__raw_readl(ocotp_base) &
+ (BM_OCOTP_CTRL_BUSY | BM_OCOTP_CTRL_ERROR)) && --timeout)
+ cpu_relax();
...which means you do not have to poll the error bit here...
quoted
+
+ 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();
...which means you can factor out a ocotp_wait_busy function and let the
code speak instead of the comments.
quoted
+
+ if (unlikely(!timeout))
+ goto error_unlock;
+
+ for (i = 0; i < count; i++, offset += 4)
+ *values++ = __raw_readl(ocotp_base + offset);
The registers in the ocotp are 16 byte aligned. Does it really make
sense to provide a function allowing to read the gaps between the
registers?
Good catch. The count was added to ease the consecutive otp word
reading, as there is bank open/close cost for otp read. What about
the following changes?
int mxs_read_ocotp(unsigned offset, size_t otp_word_cnt, u32 *values)
{
......
for (i = 0; i < otp_word_cnt; i++, offset += 0x10)
*values++ = __raw_readl(ocotp_base + offset);
......
}
I would rather make a function like this:
static u32 ocotp[0x27];
const u32 *mxs_get_ocotp(void)
{
static int once = 0;
if (once)
return ocotp
/* bank open */
for (i = 0; i < 0x27; i++)
ocotp[i] = readl(ocotp_base + 0x20 + i * 0x10)
/* bank_close */
once = 1;
return ocotp;
which is save on UP when it's not called from irq context.
Additionally I suggest a #define for 0x27 and 0x20.
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
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