These changes are the raw update to linux-4.4.6-rt14. Kernel sources

[kvmfornfv.git] / kernel / drivers / clocksource / armv7m_systick.c

diff --git a/kernel/drivers/clocksource/armv7m_systick.c b/kernel/drivers/clocksource/armv7m_systick.c
new file mode 100644 (file)
index 0000000..addfd2c
--- /dev/null
+++ b/kernel/drivers/clocksource/armv7m_systick.c
@@ -0,0 +1,79 @@
+/*
+ * Copyright (C) Maxime Coquelin 2015
+ * Author:  Maxime Coquelin <mcoquelin.stm32@gmail.com>
+ * License terms:  GNU General Public License (GPL), version 2
+ */
+
+#include <linux/kernel.h>
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/clk.h>
+#include <linux/bitops.h>
+
+#define SYST_CSR       0x00
+#define SYST_RVR       0x04
+#define SYST_CVR       0x08
+#define SYST_CALIB     0x0c
+
+#define SYST_CSR_ENABLE BIT(0)
+
+#define SYSTICK_LOAD_RELOAD_MASK 0x00FFFFFF
+
+static void __init system_timer_of_register(struct device_node *np)
+{
+       struct clk *clk = NULL;
+       void __iomem *base;
+       u32 rate;
+       int ret;
+
+       base = of_iomap(np, 0);
+       if (!base) {
+               pr_warn("system-timer: invalid base address\n");
+               return;
+       }
+
+       ret = of_property_read_u32(np, "clock-frequency", &rate);
+       if (ret) {
+               clk = of_clk_get(np, 0);
+               if (IS_ERR(clk))
+                       goto out_unmap;
+
+               ret = clk_prepare_enable(clk);
+               if (ret)
+                       goto out_clk_put;
+
+               rate = clk_get_rate(clk);
+               if (!rate)
+                       goto out_clk_disable;
+       }
+
+       writel_relaxed(SYSTICK_LOAD_RELOAD_MASK, base + SYST_RVR);
+       writel_relaxed(SYST_CSR_ENABLE, base + SYST_CSR);
+
+       ret = clocksource_mmio_init(base + SYST_CVR, "arm_system_timer", rate,
+                       200, 24, clocksource_mmio_readl_down);
+       if (ret) {
+               pr_err("failed to init clocksource (%d)\n", ret);
+               if (clk)
+                       goto out_clk_disable;
+               else
+                       goto out_unmap;
+       }
+
+       pr_info("ARM System timer initialized as clocksource\n");
+
+       return;
+
+out_clk_disable:
+       clk_disable_unprepare(clk);
+out_clk_put:
+       clk_put(clk);
+out_unmap:
+       iounmap(base);
+       pr_warn("ARM System timer register failed (%d)\n", ret);
+}
+
+CLOCKSOURCE_OF_DECLARE(arm_systick, "arm,armv7m-systick",
+                       system_timer_of_register);