From: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
To: barebox@lists.infradead.org
Subject: [PATCH 1/1] arm: add generic smp twd timer
Date: Thu, 4 Oct 2012 09:01:33 +0200 [thread overview]
Message-ID: <1349334093-9769-1-git-send-email-plagnioj@jcrosoft.com> (raw)
on Cortex A9 and Cortex A5 we have a generic timer which we can use as
clocksource
Limit the timer frequency to < 25Mhz
Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
---
arch/arm/cpu/Kconfig | 3 ++
arch/arm/cpu/Makefile | 1 +
arch/arm/cpu/smp_twd.c | 93 ++++++++++++++++++++++++++++++++++++++++
arch/arm/include/asm/smp_twd.h | 23 ++++++++++
4 files changed, 120 insertions(+)
create mode 100644 arch/arm/cpu/smp_twd.c
create mode 100644 arch/arm/include/asm/smp_twd.h
diff --git a/arch/arm/cpu/Kconfig b/arch/arm/cpu/Kconfig
index f55e862..a7a1cdb 100644
--- a/arch/arm/cpu/Kconfig
+++ b/arch/arm/cpu/Kconfig
@@ -94,3 +94,6 @@ config CACHE_L2X0
bool "Enable L2x0 PrimeCell"
depends on MMU && ARCH_HAS_L2X0
+config ARM_SMP_TWD
+ bool
+ depends on CPU_V7
diff --git a/arch/arm/cpu/Makefile b/arch/arm/cpu/Makefile
index f7ab276..c5cbdfb 100644
--- a/arch/arm/cpu/Makefile
+++ b/arch/arm/cpu/Makefile
@@ -18,5 +18,6 @@ pbl-$(CONFIG_CPU_32v6) += cache-armv6.o
obj-$(CONFIG_CPU_32v7) += cache-armv7.o
pbl-$(CONFIG_CPU_32v7) += cache-armv7.o
obj-$(CONFIG_CACHE_L2X0) += cache-l2x0.o
+obj-$(CONFIG_ARM_SMP_TWD) += smp_twd.o
pbl-y += start-pbl.o
diff --git a/arch/arm/cpu/smp_twd.c b/arch/arm/cpu/smp_twd.c
new file mode 100644
index 0000000..3825e6b
--- /dev/null
+++ b/arch/arm/cpu/smp_twd.c
@@ -0,0 +1,93 @@
+/*
+ * Copyright (C) 2012 Jean-Christophe PLAGNIOL-VILLARD <plagnio@jcrosoft.com>
+ *
+ * Under GPL v2
+ */
+#include <common.h>
+#include <init.h>
+#include <clock.h>
+#include <io.h>
+#include <driver.h>
+#include <errno.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+
+#include <asm/smp_twd.h>
+
+static __iomem void *twd_base;
+static struct clk *twd_clk;
+
+static uint64_t smp_twd_read(void)
+{
+ return ~readl(twd_base + TWD_TIMER_COUNTER);
+}
+
+static struct clocksource smp_twd_clksrc = {
+ .read = smp_twd_read,
+ .shift = 20,
+ .mask = CLOCKSOURCE_MASK(32),
+};
+
+#define SMP_TWD_MAX_FREQ (25 *1000 * 1000)
+
+void __clocksource_updatefreq_scale(struct clocksource *cs, u32 scale, u32 freq);
+
+static int smp_twd_probe(struct device_d *dev)
+{
+ u32 tick_rate;
+ u32 val;
+ int ret;
+ u32 presc = 0;
+
+ twd_clk = clk_get_sys("smp_twd", NULL);
+ if (IS_ERR(twd_clk)) {
+ ret = PTR_ERR(twd_clk);
+ pr_err("smp_twd: clock not found: %d\n", ret);
+ return ret;
+ }
+
+ ret = clk_enable(twd_clk);
+ if (ret < 0) {
+ pr_err("smp_twd: clock failed to enable: %d\n", ret);
+ clk_put(twd_clk);
+ return ret;
+ }
+
+ twd_base = dev_request_mem_region(dev, 0);
+
+ tick_rate = clk_get_rate(twd_clk);
+ if (tick_rate > SMP_TWD_MAX_FREQ) {
+ presc = tick_rate / SMP_TWD_MAX_FREQ;
+ if (presc)
+ presc--;
+ presc = min((u32)0xff, presc);
+ tick_rate /= presc + 1;
+ }
+
+ val = TWD_TIMER_CONTROL_PRESC(presc) |
+ TWD_TIMER_CONTROL_PERIODIC;
+ writel(val, twd_base + TWD_TIMER_CONTROL);
+
+ writel(0xffffffff, twd_base + TWD_TIMER_LOAD);
+
+ val = readl(twd_base + TWD_TIMER_CONTROL);
+ val |= TWD_TIMER_CONTROL_ENABLE;
+ writel(val, twd_base + TWD_TIMER_CONTROL);
+
+ smp_twd_clksrc.mult = clocksource_hz2mult(tick_rate, smp_twd_clksrc.shift);
+
+ init_clock(&smp_twd_clksrc);
+
+ return 0;
+}
+
+static struct driver_d smp_twd_driver = {
+ .name = "smp-twd",
+ .probe = smp_twd_probe,
+};
+
+static int smp_twd_init(void)
+{
+ return platform_driver_register(&smp_twd_driver);
+}
+coredevice_initcall(smp_twd_init);
diff --git a/arch/arm/include/asm/smp_twd.h b/arch/arm/include/asm/smp_twd.h
new file mode 100644
index 0000000..d461d0b
--- /dev/null
+++ b/arch/arm/include/asm/smp_twd.h
@@ -0,0 +1,23 @@
+#ifndef __ASMARM_SMP_TWD_H
+#define __ASMARM_SMP_TWD_H
+
+#define TWD_TIMER_LOAD 0x00
+#define TWD_TIMER_COUNTER 0x04
+#define TWD_TIMER_CONTROL 0x08
+#define TWD_TIMER_INTSTAT 0x0C
+
+#define TWD_WDOG_LOAD 0x20
+#define TWD_WDOG_COUNTER 0x24
+#define TWD_WDOG_CONTROL 0x28
+#define TWD_WDOG_INTSTAT 0x2C
+#define TWD_WDOG_RESETSTAT 0x30
+#define TWD_WDOG_DISABLE 0x34
+
+#define TWD_TIMER_CONTROL_ENABLE (1 << 0)
+#define TWD_TIMER_CONTROL_ONESHOT (0 << 1)
+#define TWD_TIMER_CONTROL_PERIODIC (1 << 1)
+#define TWD_TIMER_CONTROL_IT_ENABLE (1 << 2)
+
+#define TWD_TIMER_CONTROL_PRESC(x) (((x) & 0xff) << 8)
+
+#endif
--
1.7.10.4
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next reply other threads:[~2012-10-04 7:04 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-04 7:01 Jean-Christophe PLAGNIOL-VILLARD [this message]
2012-10-04 7:24 ` Sascha Hauer
2012-10-04 9:54 ` Jean-Christophe PLAGNIOL-VILLARD
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