MIPS: ralink: Add support for periodic timer irq
Adds a driver for the periodic timer found on Ralink SoC.
Signed-off-by: John Crispin <blogic@openwrt.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/5682/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/ralink/Makefile b/arch/mips/ralink/Makefile
index 38cf1a8..e37e0ec 100644
--- a/arch/mips/ralink/Makefile
+++ b/arch/mips/ralink/Makefile
@@ -6,7 +6,7 @@
# Copyright (C) 2009-2011 Gabor Juhos <juhosg@openwrt.org>
# Copyright (C) 2013 John Crispin <blogic@openwrt.org>
-obj-y := prom.o of.o reset.o clk.o irq.o
+obj-y := prom.o of.o reset.o clk.o irq.o timer.o
obj-$(CONFIG_SOC_RT288X) += rt288x.o
obj-$(CONFIG_SOC_RT305X) += rt305x.o
diff --git a/arch/mips/ralink/timer.c b/arch/mips/ralink/timer.c
new file mode 100644
index 0000000..e49241a
--- /dev/null
+++ b/arch/mips/ralink/timer.c
@@ -0,0 +1,185 @@
+/*
+ * 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.
+ *
+ * Copyright (C) 2013 John Crispin <blogic@openwrt.org>
+*/
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/interrupt.h>
+#include <linux/timer.h>
+#include <linux/of_gpio.h>
+#include <linux/clk.h>
+
+#include <asm/mach-ralink/ralink_regs.h>
+
+#define TIMER_REG_TMRSTAT 0x00
+#define TIMER_REG_TMR0LOAD 0x10
+#define TIMER_REG_TMR0CTL 0x18
+
+#define TMRSTAT_TMR0INT BIT(0)
+
+#define TMR0CTL_ENABLE BIT(7)
+#define TMR0CTL_MODE_PERIODIC BIT(4)
+#define TMR0CTL_PRESCALER 1
+#define TMR0CTL_PRESCALE_VAL (0xf - TMR0CTL_PRESCALER)
+#define TMR0CTL_PRESCALE_DIV (65536 / BIT(TMR0CTL_PRESCALER))
+
+struct rt_timer {
+ struct device *dev;
+ void __iomem *membase;
+ int irq;
+ unsigned long timer_freq;
+ unsigned long timer_div;
+};
+
+static inline void rt_timer_w32(struct rt_timer *rt, u8 reg, u32 val)
+{
+ __raw_writel(val, rt->membase + reg);
+}
+
+static inline u32 rt_timer_r32(struct rt_timer *rt, u8 reg)
+{
+ return __raw_readl(rt->membase + reg);
+}
+
+static irqreturn_t rt_timer_irq(int irq, void *_rt)
+{
+ struct rt_timer *rt = (struct rt_timer *) _rt;
+
+ rt_timer_w32(rt, TIMER_REG_TMR0LOAD, rt->timer_freq / rt->timer_div);
+ rt_timer_w32(rt, TIMER_REG_TMRSTAT, TMRSTAT_TMR0INT);
+
+ return IRQ_HANDLED;
+}
+
+
+static int rt_timer_request(struct rt_timer *rt)
+{
+ int err = request_irq(rt->irq, rt_timer_irq, IRQF_DISABLED,
+ dev_name(rt->dev), rt);
+ if (err) {
+ dev_err(rt->dev, "failed to request irq\n");
+ } else {
+ u32 t = TMR0CTL_MODE_PERIODIC | TMR0CTL_PRESCALE_VAL;
+ rt_timer_w32(rt, TIMER_REG_TMR0CTL, t);
+ }
+ return err;
+}
+
+static void rt_timer_free(struct rt_timer *rt)
+{
+ free_irq(rt->irq, rt);
+}
+
+static int rt_timer_config(struct rt_timer *rt, unsigned long divisor)
+{
+ if (rt->timer_freq < divisor)
+ rt->timer_div = rt->timer_freq;
+ else
+ rt->timer_div = divisor;
+
+ rt_timer_w32(rt, TIMER_REG_TMR0LOAD, rt->timer_freq / rt->timer_div);
+
+ return 0;
+}
+
+static int rt_timer_enable(struct rt_timer *rt)
+{
+ u32 t;
+
+ rt_timer_w32(rt, TIMER_REG_TMR0LOAD, rt->timer_freq / rt->timer_div);
+
+ t = rt_timer_r32(rt, TIMER_REG_TMR0CTL);
+ t |= TMR0CTL_ENABLE;
+ rt_timer_w32(rt, TIMER_REG_TMR0CTL, t);
+
+ return 0;
+}
+
+static void rt_timer_disable(struct rt_timer *rt)
+{
+ u32 t;
+
+ t = rt_timer_r32(rt, TIMER_REG_TMR0CTL);
+ t &= ~TMR0CTL_ENABLE;
+ rt_timer_w32(rt, TIMER_REG_TMR0CTL, t);
+}
+
+static int rt_timer_probe(struct platform_device *pdev)
+{
+ struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ struct rt_timer *rt;
+ struct clk *clk;
+
+ rt = devm_kzalloc(&pdev->dev, sizeof(*rt), GFP_KERNEL);
+ if (!rt) {
+ dev_err(&pdev->dev, "failed to allocate memory\n");
+ return -ENOMEM;
+ }
+
+ rt->irq = platform_get_irq(pdev, 0);
+ if (!rt->irq) {
+ dev_err(&pdev->dev, "failed to load irq\n");
+ return -ENOENT;
+ }
+
+ rt->membase = devm_request_and_ioremap(&pdev->dev, res);
+ if (IS_ERR(rt->membase))
+ return PTR_ERR(rt->membase);
+
+ clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(clk)) {
+ dev_err(&pdev->dev, "failed get clock rate\n");
+ return PTR_ERR(clk);
+ }
+
+ rt->timer_freq = clk_get_rate(clk) / TMR0CTL_PRESCALE_DIV;
+ if (!rt->timer_freq)
+ return -EINVAL;
+
+ rt->dev = &pdev->dev;
+ platform_set_drvdata(pdev, rt);
+
+ rt_timer_request(rt);
+ rt_timer_config(rt, 2);
+ rt_timer_enable(rt);
+
+ dev_info(&pdev->dev, "maximum frequncy is %luHz\n", rt->timer_freq);
+
+ return 0;
+}
+
+static int rt_timer_remove(struct platform_device *pdev)
+{
+ struct rt_timer *rt = platform_get_drvdata(pdev);
+
+ rt_timer_disable(rt);
+ rt_timer_free(rt);
+
+ return 0;
+}
+
+static const struct of_device_id rt_timer_match[] = {
+ { .compatible = "ralink,rt2880-timer" },
+ {},
+};
+MODULE_DEVICE_TABLE(of, rt_timer_match);
+
+static struct platform_driver rt_timer_driver = {
+ .probe = rt_timer_probe,
+ .remove = rt_timer_remove,
+ .driver = {
+ .name = "rt-timer",
+ .owner = THIS_MODULE,
+ .of_match_table = rt_timer_match
+ },
+};
+
+module_platform_driver(rt_timer_driver);
+
+MODULE_DESCRIPTION("Ralink RT2880 timer");
+MODULE_AUTHOR("John Crispin <blogic@openwrt.org");
+MODULE_LICENSE("GPL");
