From 2bb9fb8414b8ad35ed5fc6c91a34c21cef285a01 Mon Sep 17 00:00:00 2001
From: Rui Miguel Silva <rui.silva@linaro.org>
Date: Wed, 18 Dec 2019 21:52:34 +0000
Subject: [PATCH 1/2] armv7: adding generic timer access through MMIO

Upstream-Status: Pending [Not submitted to upstream yet]
Signed-off-by: Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>

This driver enables the ARMv7 generic timer.

The access to the timer registers is through memory mapping (MMIO).

This driver can be used by u-boot to access to the timer through MMIO
when arch_timer is not available in the core (access using system
instructions not possible), for example, in case of Cortex-A5.

This driver configures and enables the generic timer at
the u-boot initcall level (timer_init) before u-boot relocation.

Signed-off-by: Rui Miguel Silva <rui.silva@linaro.org>
Signed-off-by: Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>


Signed-off-by: Rui Miguel Silva <rui.silva@linaro.org>
---
 arch/arm/cpu/armv7/Makefile     |  1 +
 arch/arm/cpu/armv7/mmio_timer.c | 75 +++++++++++++++++++++++++++++++++
 scripts/config_whitelist.txt    |  1 +
 3 files changed, 77 insertions(+)
 create mode 100644 arch/arm/cpu/armv7/mmio_timer.c

diff --git a/arch/arm/cpu/armv7/Makefile b/arch/arm/cpu/armv7/Makefile
index bfbd85ae64ef..1a0a24e53110 100644
--- a/arch/arm/cpu/armv7/Makefile
+++ b/arch/arm/cpu/armv7/Makefile
@@ -28,6 +28,7 @@ obj-$(CONFIG_ARMV7_PSCI)	+= psci.o psci-common.o
 obj-$(CONFIG_IPROC) += iproc-common/
 obj-$(CONFIG_KONA) += kona-common/
 obj-$(CONFIG_SYS_ARCH_TIMER) += arch_timer.o
+obj-$(CONFIG_SYS_MMIO_TIMER) += mmio_timer.o
 
 ifneq (,$(filter s5pc1xx exynos,$(SOC)))
 obj-y += s5p-common/
diff --git a/arch/arm/cpu/armv7/mmio_timer.c b/arch/arm/cpu/armv7/mmio_timer.c
new file mode 100644
index 000000000000..edd806e06e42
--- /dev/null
+++ b/arch/arm/cpu/armv7/mmio_timer.c
@@ -0,0 +1,75 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2019, Arm Limited. All rights reserved.
+ *
+ */
+
+#include <common.h>
+#include <asm/io.h>
+#include <div64.h>
+#include <bootstage.h>
+#include <asm/global_data.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+#define CNTCTLBASE    0x1a020000UL
+#define CNTREADBASE   0x1a030000UL
+#define CNTEN         (1 << 0)
+#define CNTFCREQ      (1 << 8)
+
+static inline uint32_t mmio_read32(uintptr_t addr)
+{
+	return *(volatile uint32_t*)addr;
+}
+
+static inline void mmio_write32(uintptr_t addr, uint32_t data)
+{
+	*(volatile uint32_t*)addr = data;
+}
+
+int timer_init(void)
+{
+	/* calculate the frequency in ms */
+	gd->arch.timer_rate_hz = COUNTER_FREQUENCY / CONFIG_SYS_HZ;
+
+	/* configure CNTFID0 register: set the base frequency */
+	mmio_write32(CNTCTLBASE + 0x20, COUNTER_FREQUENCY);
+
+	/*
+	 * configure CNTCR register:
+	 *    enable the generic counter and;
+	 *    select the first frequency entry
+	 */
+	mmio_write32(CNTCTLBASE, CNTFCREQ | CNTEN);
+
+	return 0;
+}
+
+unsigned long long get_ticks(void)
+{
+	return (((u64)(mmio_read32(CNTREADBASE + 0x4)) << 32) |
+		mmio_read32(CNTREADBASE));
+}
+
+ulong get_timer(ulong base)
+{
+	return lldiv(get_ticks(), gd->arch.timer_rate_hz) - base;
+}
+
+void __udelay(unsigned long usec)
+{
+	unsigned long endtime;
+
+	endtime = lldiv((unsigned long long)usec * gd->arch.timer_rate_hz,
+			1000UL);
+
+	endtime += get_ticks();
+
+	while (get_ticks() < endtime)
+		;
+}
+
+ulong get_tbclk(void)
+{
+	return gd->arch.timer_rate_hz;
+}
diff --git a/scripts/config_whitelist.txt b/scripts/config_whitelist.txt
index ea71f9d23449..1496d9b88233 100644
--- a/scripts/config_whitelist.txt
+++ b/scripts/config_whitelist.txt
@@ -610,6 +610,7 @@ CONFIG_SYS_MMC_U_BOOT_DST
 CONFIG_SYS_MMC_U_BOOT_OFFS
 CONFIG_SYS_MMC_U_BOOT_SIZE
 CONFIG_SYS_MMC_U_BOOT_START
+CONFIG_SYS_MMIO_TIMER
 CONFIG_SYS_MOR_VAL
 CONFIG_SYS_MRAM_BASE
 CONFIG_SYS_NAND_AMASK
-- 
2.39.1