Define frequency of system counter in platform code
BL3-1 architecture setup code programs the system counter frequency
into the CNTFRQ_EL0 register. This frequency is defined by the
platform, though. This patch introduces a new platform hook that
the architecture setup code can call to retrieve this information.
In the ARM FVP port, this returns the first entry of the frequency
modes table from the memory mapped generic timer.
All system counter setup code has been removed from BL1 as some
platforms may not have initialized the system counters at this stage.
The platform specific settings done exclusively in BL1 have been moved
to BL3-1. In the ARM FVP port, this consists in enabling and
initializing the System level generic timer. Also, the frequency change
request in the counter control register has been set to 0 to make it
explicit it's using the base frequency. The CNTCR_FCREQ() macro has been
fixed in this context to give an entry number rather than a bitmask.
In future, when support for firmware update is implemented, there
is a case where BL1 platform specific code will need to program
the counter frequency. This should be implemented at that time.
This patch also updates the relevant documentation.
It properly fixes ARM-software/tf-issues#24
Change-Id: If95639b279f75d66ac0576c48a6614b5ccb0e84b
diff --git a/bl1/aarch64/bl1_arch_setup.c b/bl1/aarch64/bl1_arch_setup.c
index 4191937..417a536 100644
--- a/bl1/aarch64/bl1_arch_setup.c
+++ b/bl1/aarch64/bl1_arch_setup.c
@@ -39,7 +39,6 @@
void bl1_arch_setup(void)
{
unsigned long tmp_reg = 0;
- unsigned int counter_base_frequency;
/* Enable alignment checks and set the exception endianess to LE */
tmp_reg = read_sctlr_el3();
@@ -60,15 +59,6 @@
*/
enable_serror();
enable_debug_exceptions();
-
- /* Read the frequency from Frequency modes table */
- counter_base_frequency = mmio_read_32(SYS_CNTCTL_BASE + CNTFID_OFF);
- /* The first entry of the frequency modes table must not be 0 */
- assert(counter_base_frequency != 0);
-
- /* Program the counter frequency */
- write_cntfrq_el0(counter_base_frequency);
- return;
}
/*******************************************************************************
diff --git a/bl31/aarch64/bl31_arch_setup.c b/bl31/aarch64/bl31_arch_setup.c
index faca2a1..793b895 100644
--- a/bl31/aarch64/bl31_arch_setup.c
+++ b/bl31/aarch64/bl31_arch_setup.c
@@ -40,7 +40,7 @@
void bl31_arch_setup(void)
{
unsigned long tmp_reg = 0;
- unsigned int counter_base_frequency;
+ uint64_t counter_freq;
/* Enable alignment checks and set the exception endianness to LE */
tmp_reg = read_sctlr_el3();
@@ -62,14 +62,9 @@
enable_serror();
enable_debug_exceptions();
- /* Read the frequency from Frequency modes table */
- counter_base_frequency = mmio_read_32(SYS_CNTCTL_BASE + CNTFID_OFF);
- /* The first entry of the frequency modes table must not be 0 */
- assert(counter_base_frequency != 0);
-
/* Program the counter frequency */
- write_cntfrq_el0(counter_base_frequency);
- return;
+ counter_freq = plat_get_syscnt_freq();
+ write_cntfrq_el0(counter_freq);
}
/*******************************************************************************
diff --git a/docs/firmware-design.md b/docs/firmware-design.md
index 2bf57ca..8c635a9 100644
--- a/docs/firmware-design.md
+++ b/docs/firmware-design.md
@@ -151,13 +151,6 @@
and Advanced SIMD execution are configured to not trap to EL3 by
clearing the `CPTR_EL3.TFP` bit.
- - `CNTFRQ_EL0`. The `CNTFRQ_EL0` register is programmed with the base
- frequency of the system counter, which is retrieved from the first entry
- in the frequency modes table.
-
- - Generic Timer. The system level implementation of the generic timer is
- enabled through the memory mapped interface.
-
#### Platform initialization
BL1 enables issuing of snoop and DVM (Distributed Virtual Memory) requests from
@@ -291,7 +284,8 @@
since this is the only mechanism to access the runtime services implemented by
BL3-1 (PSCI for example). BL3-1 checks each SMC for validity as specified by
the [SMC calling convention PDD][SMCCC] before passing control to the required
-SMC handler routine.
+SMC handler routine. BL3-1 programs the `CNTFRQ_EL0` register with the clock
+frequency of the system counter, which is provided by the platform.
#### Platform initialization
@@ -299,7 +293,8 @@
software to function correctly. It also retrieves entrypoint information for
the BL3-3 image loaded by BL2 from the platform defined memory address populated
by BL2. BL3-1 also initializes UART0 (PL011 console), which enables
-access to the `printf` family of functions in BL3-1
+access to the `printf` family of functions in BL3-1. It enables the system
+level implementation of the generic timer through the memory mapped interface.
* GICv2 initialization:
diff --git a/docs/porting-guide.md b/docs/porting-guide.md
index 56467fb..5dca6fd 100644
--- a/docs/porting-guide.md
+++ b/docs/porting-guide.md
@@ -208,6 +208,13 @@
platform) & `platform_get_stack()` (to return the base address of that
stack) (see [../plat/common/aarch64/platform_helpers.S]).
+* **Function : uint64_t plat_get_syscnt_freq(void)**
+
+ This function is used by the architecture setup code to retrieve the
+ counter frequency for the CPU's generic timer. This value will be
+ programmed into the `CNTFRQ_EL0` register.
+ In the ARM FVP port, it returns the base frequency of the system counter,
+ which is retrieved from the first entry in the frequency modes table.
2.2 Common optional modifications
---------------------------------
@@ -446,9 +453,6 @@
for performing any remaining platform-specific setup that can occur after the
MMU and data cache have been enabled.
-In the ARM FVP port, it zeros out the ZI section and enables the system level
-implementation of the generic timer counter.
-
This function is also responsible for initializing the storage abstraction layer
which is used to load further bootloader images.
@@ -771,6 +775,7 @@
The ARM FVP port does the following:
* Initializes the generic interrupt controller.
* Configures the CLCD controller.
+* Enables system-level implementation of the generic timer counter.
* Grants access to the system counter timer module
* Initializes the FVP power controller device
* Detects the system topology.
diff --git a/include/aarch64/arch.h b/include/aarch64/arch.h
index 3e67282..a41e82b 100644
--- a/include/aarch64/arch.h
+++ b/include/aarch64/arch.h
@@ -78,7 +78,7 @@
#define CNTCR_EN (1 << 0)
#define CNTCR_HDBG (1 << 1)
-#define CNTCR_FCREQ(x) (1 << (8 + (x)))
+#define CNTCR_FCREQ(x) ((x) << 8)
/*******************************************************************************
* System register bit definitions
diff --git a/plat/fvp/aarch64/plat_common.c b/plat/fvp/aarch64/plat_common.c
index d44ccb6..a5d9f1d 100644
--- a/plat/fvp/aarch64/plat_common.c
+++ b/plat/fvp/aarch64/plat_common.c
@@ -248,3 +248,16 @@
{
return NS_IMAGE_OFFSET;
}
+
+uint64_t plat_get_syscnt_freq(void)
+{
+ uint64_t counter_base_frequency;
+
+ /* Read the frequency from Frequency modes table */
+ counter_base_frequency = mmio_read_32(SYS_CNTCTL_BASE + CNTFID_OFF);
+
+ /* The first entry of the frequency modes table must not be 0 */
+ assert(counter_base_frequency != 0);
+
+ return counter_base_frequency;
+}
diff --git a/plat/fvp/bl1_plat_setup.c b/plat/fvp/bl1_plat_setup.c
index d4fd81b..67694f4 100644
--- a/plat/fvp/bl1_plat_setup.c
+++ b/plat/fvp/bl1_plat_setup.c
@@ -114,9 +114,6 @@
{
/* Initialise the IO layer and register platform IO devices */
io_setup();
-
- /* Enable and initialize the System level generic timer */
- mmio_write_32(SYS_CNTCTL_BASE + CNTCR_OFF, CNTCR_EN);
}
diff --git a/plat/fvp/bl31_plat_setup.c b/plat/fvp/bl31_plat_setup.c
index 07987e4..9bf83eb 100644
--- a/plat/fvp/bl31_plat_setup.c
+++ b/plat/fvp/bl31_plat_setup.c
@@ -29,9 +29,9 @@
*/
#include <platform.h>
+#include <arch.h>
#include <fvp_pwrc.h>
#include <console.h>
-#include <bl_common.h>
/*******************************************************************************
* Declarations of linker defined symbols which will help us find the layout
@@ -141,6 +141,9 @@
mmio_write_32(VE_SYSREGS_BASE + V2M_SYS_CFGCTRL,
(1ull << 31) | (1 << 30) | (7 << 20) | (0 << 16));
+ /* Enable and initialize the System level generic timer */
+ mmio_write_32(SYS_CNTCTL_BASE + CNTCR_OFF, CNTCR_FCREQ(0) | CNTCR_EN);
+
/* Allow access to the System counter timer module */
reg_val = (1 << CNTACR_RPCT_SHIFT) | (1 << CNTACR_RVCT_SHIFT);
reg_val |= (1 << CNTACR_RFRQ_SHIFT) | (1 << CNTACR_RVOFF_SHIFT);
diff --git a/plat/fvp/platform.h b/plat/fvp/platform.h
index 53f14aa..5f4adc3 100644
--- a/plat/fvp/platform.h
+++ b/plat/fvp/platform.h
@@ -346,6 +346,7 @@
extern void plat_report_exception(unsigned long);
extern unsigned long plat_get_ns_image_entrypoint(void);
extern unsigned long platform_get_stack(unsigned long mpidr);
+extern uint64_t plat_get_syscnt_freq(void);
/* Declarations for fvp_gic.c */
extern void gic_cpuif_deactivate(unsigned int);