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Date: Mon, 18 Nov 2013 19:40:47 +0900
From: Alexandre Courbot <acourbot@...dia.com>
To: Stephen Warren <swarren@...dotorg.org>,
Thierry Reding <thierry.reding@...il.com>,
Peter De Schrijver <pdeschrijver@...dia.com>,
Prashant Gaikwad <pgaikwad@...dia.com>
CC: <linux-tegra@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
Alexandre Courbot <acourbot@...dia.com>
Subject: [PATCH] ARM: tegra: properly use FUSE clock
FUSE clock is enabled by most bootloaders, but we cannot expect it to be
on in all contexts (e.g. kexec).
This patch adds a FUSE clkdev to all Tegra platforms and makes sure
it is enabled before touching FUSE registers. tegra_init_fuse() is
invoked during very early boot and thus cannot rely on the clock
framework ; therefore the FUSE clock is forcibly enabled using a
register write in that function, and remains that way until the
clock framework can be used.
Signed-off-by: Alexandre Courbot <acourbot@...dia.com>
---
arch/arm/mach-tegra/fuse.c | 41 +++++++++++++++++++++++++++++++++++++++-
drivers/clk/tegra/clk-tegra114.c | 1 +
drivers/clk/tegra/clk-tegra124.c | 1 +
drivers/clk/tegra/clk-tegra20.c | 1 +
4 files changed, 43 insertions(+), 1 deletion(-)
diff --git a/arch/arm/mach-tegra/fuse.c b/arch/arm/mach-tegra/fuse.c
index 9a4e910c3796..3b9191b930b5 100644
--- a/arch/arm/mach-tegra/fuse.c
+++ b/arch/arm/mach-tegra/fuse.c
@@ -22,6 +22,7 @@
#include <linux/io.h>
#include <linux/export.h>
#include <linux/random.h>
+#include <linux/clk.h>
#include <linux/tegra-soc.h>
#include "fuse.h"
@@ -54,6 +55,7 @@ int tegra_cpu_speedo_id; /* only exist in Tegra30 and later */
int tegra_soc_speedo_id;
enum tegra_revision tegra_revision;
+static struct clk *fuse_clk;
static int tegra_fuse_spare_bit;
static void (*tegra_init_speedo_data)(void);
@@ -77,6 +79,22 @@ static const char *tegra_revision_name[TEGRA_REVISION_MAX] = {
[TEGRA_REVISION_A04] = "A04",
};
+static void tegra_fuse_enable_clk(void)
+{
+ if (IS_ERR(fuse_clk))
+ fuse_clk = clk_get_sys("fuse-tegra", "fuse");
+ if (IS_ERR(fuse_clk))
+ return;
+ clk_prepare_enable(fuse_clk);
+}
+
+static void tegra_fuse_disable_clk(void)
+{
+ if (IS_ERR(fuse_clk))
+ return;
+ clk_disable_unprepare(fuse_clk);
+}
+
u32 tegra_fuse_readl(unsigned long offset)
{
return tegra_apb_readl(TEGRA_FUSE_BASE + offset);
@@ -84,7 +102,15 @@ u32 tegra_fuse_readl(unsigned long offset)
bool tegra_spare_fuse(int bit)
{
- return tegra_fuse_readl(tegra_fuse_spare_bit + bit * 4);
+ bool ret;
+
+ tegra_fuse_enable_clk();
+
+ ret = tegra_fuse_readl(tegra_fuse_spare_bit + bit * 4);
+
+ tegra_fuse_disable_clk();
+
+ return ret;
}
static enum tegra_revision tegra_get_revision(u32 id)
@@ -113,10 +139,14 @@ static void tegra_get_process_id(void)
{
u32 reg;
+ tegra_fuse_enable_clk();
+
reg = tegra_fuse_readl(tegra_fuse_spare_bit);
tegra_cpu_process_id = (reg >> 6) & 3;
reg = tegra_fuse_readl(tegra_fuse_spare_bit);
tegra_core_process_id = (reg >> 12) & 3;
+
+ tegra_fuse_disable_clk();
}
u32 tegra_read_chipid(void)
@@ -159,6 +189,15 @@ void __init tegra_init_fuse(void)
reg |= 1 << 28;
writel(reg, IO_ADDRESS(TEGRA_CLK_RESET_BASE + 0x48));
+ /*
+ * Enable FUSE clock. This needs to be hardcoded because the clock
+ * subsystem is not active during early boot.
+ */
+ reg = readl(IO_ADDRESS(TEGRA_CLK_RESET_BASE + 0x14));
+ reg |= 1 << 7;
+ writel(reg, IO_ADDRESS(TEGRA_CLK_RESET_BASE + 0x14));
+ fuse_clk = ERR_PTR(-EINVAL);
+
reg = tegra_fuse_readl(FUSE_SKU_INFO);
randomness[0] = reg;
tegra_sku_id = reg & 0xFF;
diff --git a/drivers/clk/tegra/clk-tegra114.c b/drivers/clk/tegra/clk-tegra114.c
index dbab27f773b5..a83fdfd19bfc 100644
--- a/drivers/clk/tegra/clk-tegra114.c
+++ b/drivers/clk/tegra/clk-tegra114.c
@@ -925,6 +925,7 @@ static struct tegra_devclk devclks[] __initdata = {
{ .con_id = "sclk", .dt_id = TEGRA114_CLK_SCLK },
{ .con_id = "hclk", .dt_id = TEGRA114_CLK_HCLK },
{ .con_id = "pclk", .dt_id = TEGRA114_CLK_PCLK },
+ { .con_id = "fuse", .dev_id = "fuse-tegra", .dt_id = TEGRA114_CLK_FUSE },
{ .dev_id = "rtc-tegra", .dt_id = TEGRA114_CLK_RTC },
{ .dev_id = "timer", .dt_id = TEGRA114_CLK_TIMER },
};
diff --git a/drivers/clk/tegra/clk-tegra124.c b/drivers/clk/tegra/clk-tegra124.c
index 266e80b51d38..0a324a2d7309 100644
--- a/drivers/clk/tegra/clk-tegra124.c
+++ b/drivers/clk/tegra/clk-tegra124.c
@@ -1007,6 +1007,7 @@ static struct tegra_devclk devclks[] __initdata = {
{ .con_id = "sclk", .dt_id = TEGRA124_CLK_SCLK },
{ .con_id = "hclk", .dt_id = TEGRA124_CLK_HCLK },
{ .con_id = "pclk", .dt_id = TEGRA124_CLK_PCLK },
+ { .con_id = "fuse", .dev_id = "fuse-tegra", .dt_id = TEGRA124_CLK_FUSE },
{ .dev_id = "rtc-tegra", .dt_id = TEGRA124_CLK_RTC },
{ .dev_id = "timer", .dt_id = TEGRA124_CLK_TIMER },
};
diff --git a/drivers/clk/tegra/clk-tegra20.c b/drivers/clk/tegra/clk-tegra20.c
index 58faac5f509e..48dca0f4762a 100644
--- a/drivers/clk/tegra/clk-tegra20.c
+++ b/drivers/clk/tegra/clk-tegra20.c
@@ -452,6 +452,7 @@ static struct tegra_devclk devclks[] __initdata = {
{ .con_id = "sclk", .dt_id = TEGRA20_CLK_SCLK },
{ .con_id = "hclk", .dt_id = TEGRA20_CLK_HCLK },
{ .con_id = "pclk", .dt_id = TEGRA20_CLK_PCLK },
+ { .con_id = "fuse", .dev_id = "fuse-tegra", .dt_id = TEGRA20_CLK_FUSE },
{ .con_id = "twd", .dt_id = TEGRA20_CLK_TWD },
{ .con_id = "audio", .dt_id = TEGRA20_CLK_AUDIO },
{ .con_id = "audio_2x", .dt_id = TEGRA20_CLK_AUDIO_2X },
--
1.8.4.2
--
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