arm64: move from arm_generic to arm_arch_timer

The arch_timer driver supports a superset of the functionality of the
arm_generic driver, and is not tied to a particular arch.

This patch moves arm64 to use the arch_timer driver, gaining additional
functionality in doing so, and removes the (now unused) arm_generic
driver. Timer-related hooks specific to arm64 are moved into
arch/arm64/kernel/time.c.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>

arch/arm64/Kconfig

@@ -3,6 +3,7 @@ config ARM64
 	select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
 	select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
 	select ARM_AMBA
+	select ARM_ARCH_TIMER
 	select CLONE_BACKWARDS
 	select COMMON_CLK
 	select GENERIC_CLOCKEVENTS

arch/arm64/include/asm/arch_timer.h

@@ -0,0 +1,133 @@
+/*
+ * arch/arm64/include/asm/arch_timer.h
+ *
+ * Copyright (C) 2012 ARM Ltd.
+ * Author: Marc Zyngier <marc.zyngier@arm.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef __ASM_ARCH_TIMER_H
+#define __ASM_ARCH_TIMER_H
+
+#include <asm/barrier.h>
+
+#include <linux/init.h>
+#include <linux/types.h>
+
+#include <clocksource/arm_arch_timer.h>
+
+static inline void arch_timer_reg_write(int access, int reg, u32 val)
+{
+	if (access == ARCH_TIMER_PHYS_ACCESS) {
+		switch (reg) {
+		case ARCH_TIMER_REG_CTRL:
+			asm volatile("msr cntp_ctl_el0,  %0" : : "r" (val));
+			break;
+		case ARCH_TIMER_REG_TVAL:
+			asm volatile("msr cntp_tval_el0, %0" : : "r" (val));
+			break;
+		default:
+			BUILD_BUG();
+		}
+	} else if (access == ARCH_TIMER_VIRT_ACCESS) {
+		switch (reg) {
+		case ARCH_TIMER_REG_CTRL:
+			asm volatile("msr cntv_ctl_el0,  %0" : : "r" (val));
+			break;
+		case ARCH_TIMER_REG_TVAL:
+			asm volatile("msr cntv_tval_el0, %0" : : "r" (val));
+			break;
+		default:
+			BUILD_BUG();
+		}
+	} else {
+		BUILD_BUG();
+	}
+
+	isb();
+}
+
+static inline u32 arch_timer_reg_read(int access, int reg)
+{
+	u32 val;
+
+	if (access == ARCH_TIMER_PHYS_ACCESS) {
+		switch (reg) {
+		case ARCH_TIMER_REG_CTRL:
+			asm volatile("mrs %0,  cntp_ctl_el0" : "=r" (val));
+			break;
+		case ARCH_TIMER_REG_TVAL:
+			asm volatile("mrs %0, cntp_tval_el0" : "=r" (val));
+			break;
+		default:
+			BUILD_BUG();
+		}
+	} else if (access == ARCH_TIMER_VIRT_ACCESS) {
+		switch (reg) {
+		case ARCH_TIMER_REG_CTRL:
+			asm volatile("mrs %0,  cntv_ctl_el0" : "=r" (val));
+			break;
+		case ARCH_TIMER_REG_TVAL:
+			asm volatile("mrs %0, cntv_tval_el0" : "=r" (val));
+			break;
+		default:
+			BUILD_BUG();
+		}
+	} else {
+		BUILD_BUG();
+	}
+
+	return val;
+}
+
+static inline u32 arch_timer_get_cntfrq(void)
+{
+	u32 val;
+	asm volatile("mrs %0,   cntfrq_el0" : "=r" (val));
+	return val;
+}
+
+static inline void __cpuinit arch_counter_set_user_access(void)
+{
+	u32 cntkctl;
+
+	/* Disable user access to the timers and the physical counter. */
+	asm volatile("mrs	%0, cntkctl_el1" : "=r" (cntkctl));
+	cntkctl &= ~((3 << 8) | (1 << 0));
+
+	/* Enable user access to the virtual counter and frequency. */
+	cntkctl |= (1 << 1);
+	asm volatile("msr	cntkctl_el1, %0" : : "r" (cntkctl));
+}
+
+static inline u64 arch_counter_get_cntpct(void)
+{
+	u64 cval;
+
+	isb();
+	asm volatile("mrs %0, cntpct_el0" : "=r" (cval));
+
+	return cval;
+}
+
+static inline u64 arch_counter_get_cntvct(void)
+{
+	u64 cval;
+
+	isb();
+	asm volatile("mrs %0, cntvct_el0" : "=r" (cval));
+
+	return cval;
+}
+
+#endif

arch/arm64/kernel/time.c

@@ -31,8 +31,9 @@
 #include <linux/syscore_ops.h>
 #include <linux/timer.h>
 #include <linux/irq.h>
+#include <linux/delay.h>
 
-#include <clocksource/arm_generic.h>
+#include <clocksource/arm_arch_timer.h>
 
 #include <asm/thread_info.h>
 #include <asm/stacktrace.h>
@@ -59,7 +60,31 @@ unsigned long profile_pc(struct pt_regs *regs)
 EXPORT_SYMBOL(profile_pc);
 #endif
 
+static u64 sched_clock_mult __read_mostly;
+
+unsigned long long notrace sched_clock(void)
+{
+	return arch_timer_read_counter() * sched_clock_mult;
+}
+
+int read_current_timer(unsigned long *timer_value)
+{
+	*timer_value = arch_timer_read_counter();
+	return 0;
+}
+
 void __init time_init(void)
 {
-	arm_generic_timer_init();
+	u32 arch_timer_rate;
+
+	if (arch_timer_init())
+		panic("Unable to initialise architected timer.\n");
+
+	arch_timer_rate = arch_timer_get_rate();
+
+	/* Cache the sched_clock multiplier to save a divide in the hot path. */
+	sched_clock_mult = NSEC_PER_SEC / arch_timer_rate;
+
+	/* Calibrate the delay loop directly */
+	lpj_fine = arch_timer_rate / HZ;
 }

drivers/clocksource/Kconfig

@@ -54,10 +54,5 @@ config CLKSRC_DBX500_PRCMU_SCHED_CLOCK
 	help
 	  Use the always on PRCMU Timer as sched_clock
 
-config CLKSRC_ARM_GENERIC
-	def_bool y if ARM64
-	help
-	  This option enables support for the ARM generic timer.
-
 config ARM_ARCH_TIMER
 	bool

drivers/clocksource/Makefile

@@ -17,5 +17,4 @@ obj-$(CONFIG_ARMADA_370_XP_TIMER)	+= time-armada-370-xp.o
 obj-$(CONFIG_ARCH_BCM2835)	+= bcm2835_timer.o
 obj-$(CONFIG_SUNXI_TIMER)	+= sunxi_timer.o
 
-obj-$(CONFIG_CLKSRC_ARM_GENERIC)	+= arm_generic.o
 obj-$(CONFIG_ARM_ARCH_TIMER)		+= arm_arch_timer.o

drivers/clocksource/arm_arch_timer.c

@@ -338,6 +338,7 @@ static int __init arch_timer_register(void)
 
 static const struct of_device_id arch_timer_of_match[] __initconst = {
 	{ .compatible	= "arm,armv7-timer",	},
+	{ .compatible	= "arm,armv8-timer",	},
 	{},
 };