Commit cdcb5a07 authored by Alexandre Courbot's avatar Alexandre Courbot Committed by Stephen Warren
Browse files

ARM: tegra: switch FUSE clock on before usage 



FUSE clock is enabled by most bootloaders, but we cannot expect it to be
on in all contexts (e.g. kexec).

Ensure the FUSE clock is enabled before any of its registers is touched.
Since FUSE is touched very early during system boot (before the clock
devices are registered), directly manipulate the clock register bit in
case the clock device cannot be acquired.

Signed-off-by: default avatarAlexandre Courbot <acourbot@nvidia.com>
Signed-off-by: default avatarStephen Warren <swarren@nvidia.com>
parent 6ce4eac1

arch/arm/mach-tegra/fuse.c

+40 −1
Original line number Diff line number Diff line
@@ -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(NULL, "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;

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