target/linux/ramips/patches-3.10/0011-MIPS-ralink-add-support-for-systick-timer-found-on-n.patch

   1 From 3b511d972b556712f89ccc68825c0ec8f398dc5c Mon Sep 17 00:00:00 2001
   2 From: John Crispin <blogic@openwrt.org>
   3 Date: Sun, 28 Jul 2013 13:46:09 +0200
   4 Subject: [PATCH 11/25] MIPS: ralink: add support for systick timer found on
   5  newer ralink SoC
   6
   7 Newer Ralink SoC (MT7620x and RT5350) have a 50KHz clock that runs independent
   8 of the SoC master clock. If we want to automatic frequency scaling to work we
   9 need to use the systick timer as the clock source.
  10
  11 Signed-off-by: John Crispin <blogic@openwrt.org>
  12 ---
  13  arch/mips/ralink/Kconfig       |    7 ++
  14  arch/mips/ralink/Makefile      |    2 +
  15  arch/mips/ralink/cevt-rt3352.c |  145 ++++++++++++++++++++++++++++++++++++++++
  16  3 files changed, 154 insertions(+)
  17  create mode 100644 arch/mips/ralink/cevt-rt3352.c
  18
  19 --- a/arch/mips/ralink/Kconfig
  20 +++ b/arch/mips/ralink/Kconfig
  21 @@ -1,5 +1,12 @@
  22  if RALINK
  23
  24 +config CLKEVT_RT3352
  25 +       bool "Systick Clockevent source"
  26 +       depends on SOC_RT305X || SOC_MT7620
  27 +       default y
  28 +       select CLKSRC_OF
  29 +       select CLKSRC_MMIO
  30 +
  31  choice
  32         prompt "Ralink SoC selection"
  33         default SOC_RT305X
  34 --- a/arch/mips/ralink/Makefile
  35 +++ b/arch/mips/ralink/Makefile
  36 @@ -8,6 +8,8 @@
  37
  38  obj-y := prom.o of.o reset.o clk.o irq.o timer.o
  39
  40 +obj-$(CONFIG_CLKEVT_RT3352) += cevt-rt3352.o
  41 +
  42  obj-$(CONFIG_SOC_RT288X) += rt288x.o
  43  obj-$(CONFIG_SOC_RT305X) += rt305x.o
  44  obj-$(CONFIG_SOC_RT3883) += rt3883.o
  45 --- /dev/null
  46 +++ b/arch/mips/ralink/cevt-rt3352.c
  47 @@ -0,0 +1,145 @@
  48 +/*
  49 + * This file is subject to the terms and conditions of the GNU General Public
  50 + * License.  See the file "COPYING" in the main directory of this archive
  51 + * for more details.
  52 + *
  53 + * Copyright (C) 2013 by John Crispin <blogic@openwrt.org>
  54 + */
  55 +
  56 +#include <linux/clockchips.h>
  57 +#include <linux/clocksource.h>
  58 +#include <linux/interrupt.h>
  59 +#include <linux/reset.h>
  60 +#include <linux/init.h>
  61 +#include <linux/time.h>
  62 +#include <linux/of.h>
  63 +#include <linux/of_irq.h>
  64 +#include <linux/of_address.h>
  65 +
  66 +#include <asm/mach-ralink/ralink_regs.h>
  67 +
  68 +#define SYSTICK_FREQ           (50 * 1000)
  69 +
  70 +#define SYSTICK_CONFIG         0x00
  71 +#define SYSTICK_COMPARE                0x04
  72 +#define SYSTICK_COUNT          0x08
  73 +
  74 +/* route systick irq to mips irq 7 instead of the r4k-timer */
  75 +#define CFG_EXT_STK_EN         0x2
  76 +/* enable the counter */
  77 +#define CFG_CNT_EN             0x1
  78 +
  79 +struct systick_device {
  80 +       void __iomem *membase;
  81 +       struct clock_event_device dev;
  82 +       int irq_requested;
  83 +       int freq_scale;
  84 +};
  85 +
  86 +static void systick_set_clock_mode(enum clock_event_mode mode,
  87 +                               struct clock_event_device *evt);
  88 +
  89 +static int systick_next_event(unsigned long delta,
  90 +                               struct clock_event_device *evt)
  91 +{
  92 +       struct systick_device *sdev;
  93 +       u32 count;
  94 +
  95 +       sdev = container_of(evt, struct systick_device, dev);
  96 +       count = ioread32(sdev->membase + SYSTICK_COUNT);
  97 +       count = (count + delta) % SYSTICK_FREQ;
  98 +       iowrite32(count + delta, sdev->membase + SYSTICK_COMPARE);
  99 +
 100 +       return 0;
 101 +}
 102 +
 103 +static void systick_event_handler(struct clock_event_device *dev)
 104 +{
 105 +       /* noting to do here */
 106 +}
 107 +
 108 +static irqreturn_t systick_interrupt(int irq, void *dev_id)
 109 +{
 110 +       struct clock_event_device *dev = (struct clock_event_device *) dev_id;
 111 +
 112 +       dev->event_handler(dev);
 113 +
 114 +       return IRQ_HANDLED;
 115 +}
 116 +
 117 +static struct systick_device systick = {
 118 +       .dev = {
 119 +               /*
 120 +                * cevt-r4k uses 300, make sure systick
 121 +                * gets used if available
 122 +                */
 123 +               .rating         = 310,
 124 +               .features       = CLOCK_EVT_FEAT_ONESHOT,
 125 +               .set_next_event = systick_next_event,
 126 +               .set_mode       = systick_set_clock_mode,
 127 +               .event_handler  = systick_event_handler,
 128 +       },
 129 +};
 130 +
 131 +static struct irqaction systick_irqaction = {
 132 +       .handler = systick_interrupt,
 133 +       .flags = IRQF_PERCPU | IRQF_TIMER,
 134 +       .dev_id = &systick.dev,
 135 +};
 136 +
 137 +static void systick_set_clock_mode(enum clock_event_mode mode,
 138 +                               struct clock_event_device *evt)
 139 +{
 140 +       struct systick_device *sdev;
 141 +
 142 +       sdev = container_of(evt, struct systick_device, dev);
 143 +
 144 +       switch (mode) {
 145 +       case CLOCK_EVT_MODE_ONESHOT:
 146 +               if (!sdev->irq_requested)
 147 +                       setup_irq(systick.dev.irq, &systick_irqaction);
 148 +               sdev->irq_requested = 1;
 149 +               iowrite32(CFG_EXT_STK_EN | CFG_CNT_EN,
 150 +                               systick.membase + SYSTICK_CONFIG);
 151 +               break;
 152 +
 153 +       case CLOCK_EVT_MODE_SHUTDOWN:
 154 +               if (sdev->irq_requested)
 155 +                       free_irq(systick.dev.irq, &systick_irqaction);
 156 +               sdev->irq_requested = 0;
 157 +               iowrite32(0, systick.membase + SYSTICK_CONFIG);
 158 +               break;
 159 +
 160 +       default:
 161 +               pr_err("%s: Unhandeled mips clock_mode\n", systick.dev.name);
 162 +               break;
 163 +       }
 164 +}
 165 +
 166 +static void __init ralink_systick_init(struct device_node *np)
 167 +{
 168 +       systick.membase = of_iomap(np, 0);
 169 +       if (!systick.membase)
 170 +               return;
 171 +
 172 +       systick_irqaction.name = np->name;
 173 +       systick.dev.name = np->name;
 174 +       clockevents_calc_mult_shift(&systick.dev, SYSTICK_FREQ, 60);
 175 +       systick.dev.max_delta_ns = clockevent_delta2ns(0x7fff, &systick.dev);
 176 +       systick.dev.min_delta_ns = clockevent_delta2ns(0x3, &systick.dev);
 177 +       systick.dev.irq = irq_of_parse_and_map(np, 0);
 178 +       if (!systick.dev.irq) {
 179 +               pr_err("%s: request_irq failed", np->name);
 180 +               return;
 181 +       }
 182 +
 183 +       clocksource_mmio_init(systick.membase + SYSTICK_COUNT, np->name,
 184 +                       SYSTICK_FREQ, 301, 16, clocksource_mmio_readl_up);
 185 +
 186 +       clockevents_register_device(&systick.dev);
 187 +
 188 +       pr_info("%s: runing - mult: %d, shift: %d\n",
 189 +                       np->name, systick.dev.mult, systick.dev.shift);
 190 +}
 191 +
 192 +CLOCKSOURCE_OF_DECLARE(systick, "ralink,cevt-systick", ralink_systick_init);