drivers/clocksource/asm9260_timer.c

   1 /*
   2  * Copyright (C) 2014 Oleksij Rempel <linux@rempel-privat.de>
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version 2
   7  * of the License, or (at your option) any later version.
   8  */
   9
  10 #include <linux/kernel.h>
  11 #include <linux/init.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/sched.h>
  14 #include <linux/clk.h>
  15 #include <linux/clocksource.h>
  16 #include <linux/clockchips.h>
  17 #include <linux/io.h>
  18 #include <linux/of.h>
  19 #include <linux/of_address.h>
  20 #include <linux/of_irq.h>
  21 #include <linux/bitops.h>
  22
  23 #define DRIVER_NAME     "asm9260-timer"
  24
  25 /*
  26  * this device provide 4 offsets for each register:
  27  * 0x0 - plain read write mode
  28  * 0x4 - set mode, OR logic.
  29  * 0x8 - clr mode, XOR logic.
  30  * 0xc - togle mode.
  31  */
  32 #define SET_REG 4
  33 #define CLR_REG 8
  34
  35 #define HW_IR           0x0000 /* RW. Interrupt */
  36 #define BM_IR_CR0       BIT(4)
  37 #define BM_IR_MR3       BIT(3)
  38 #define BM_IR_MR2       BIT(2)
  39 #define BM_IR_MR1       BIT(1)
  40 #define BM_IR_MR0       BIT(0)
  41
  42 #define HW_TCR          0x0010 /* RW. Timer controller */
  43 /* BM_C*_RST
  44  * Timer Counter and the Prescale Counter are synchronously reset on the
  45  * next positive edge of PCLK. The counters remain reset until TCR[1] is
  46  * returned to zero. */
  47 #define BM_C3_RST       BIT(7)
  48 #define BM_C2_RST       BIT(6)
  49 #define BM_C1_RST       BIT(5)
  50 #define BM_C0_RST       BIT(4)
  51 /* BM_C*_EN
  52  * 1 - Timer Counter and Prescale Counter are enabled for counting
  53  * 0 - counters are disabled */
  54 #define BM_C3_EN        BIT(3)
  55 #define BM_C2_EN        BIT(2)
  56 #define BM_C1_EN        BIT(1)
  57 #define BM_C0_EN        BIT(0)
  58
  59 #define HW_DIR          0x0020 /* RW. Direction? */
  60 /* 00 - count up
  61  * 01 - count down
  62  * 10 - ?? 2^n/2 */
  63 #define BM_DIR_COUNT_UP         0
  64 #define BM_DIR_COUNT_DOWN       1
  65 #define BM_DIR0_SHIFT   0
  66 #define BM_DIR1_SHIFT   4
  67 #define BM_DIR2_SHIFT   8
  68 #define BM_DIR3_SHIFT   12
  69 #define BM_DIR_DEFAULT          (BM_DIR_COUNT_UP << BM_DIR0_SHIFT | \
  70                                  BM_DIR_COUNT_UP << BM_DIR1_SHIFT | \
  71                                  BM_DIR_COUNT_UP << BM_DIR2_SHIFT | \
  72                                  BM_DIR_COUNT_UP << BM_DIR3_SHIFT)
  73
  74 #define HW_TC0          0x0030 /* RO. Timer counter 0 */
  75 /* HW_TC*. Timer counter owerflow (0xffff.ffff to 0x0000.0000) do not generate
  76  * interrupt. This registers can be used to detect overflow */
  77 #define HW_TC1          0x0040
  78 #define HW_TC2          0x0050
  79 #define HW_TC3          0x0060
  80
  81 #define HW_PR           0x0070 /* RW. prescaler */
  82 #define BM_PR_DISABLE   0
  83 #define HW_PC           0x0080 /* RO. Prescaler counter */
  84 #define HW_MCR          0x0090 /* RW. Match control */
  85 /* enable interrupt on match */
  86 #define BM_MCR_INT_EN(n)        (1 << (n * 3 + 0))
  87 /* enable TC reset on match */
  88 #define BM_MCR_RES_EN(n)        (1 << (n * 3 + 1))
  89 /* enable stop TC on match */
  90 #define BM_MCR_STOP_EN(n)       (1 << (n * 3 + 2))
  91
  92 #define HW_MR0          0x00a0 /* RW. Match reg */
  93 #define HW_MR1          0x00b0
  94 #define HW_MR2          0x00C0
  95 #define HW_MR3          0x00D0
  96
  97 #define HW_CTCR         0x0180 /* Counter control */
  98 #define BM_CTCR0_SHIFT  0
  99 #define BM_CTCR1_SHIFT  2
 100 #define BM_CTCR2_SHIFT  4
 101 #define BM_CTCR3_SHIFT  6
 102 #define BM_CTCR_TM      0       /* Timer mode. Every rising PCLK edge. */
 103 #define BM_CTCR_DEFAULT (BM_CTCR_TM << BM_CTCR0_SHIFT | \
 104                          BM_CTCR_TM << BM_CTCR1_SHIFT | \
 105                          BM_CTCR_TM << BM_CTCR2_SHIFT | \
 106                          BM_CTCR_TM << BM_CTCR3_SHIFT)
 107
 108 static struct asm9260_timer_priv {
 109         void __iomem *base;
 110         unsigned long ticks_per_jiffy;
 111 } priv;
 112
 113 static int asm9260_timer_set_next_event(unsigned long delta,
 114                                          struct clock_event_device *evt)
 115 {
 116         /* configure match count for TC0 */
 117         writel_relaxed(delta, priv.base + HW_MR0);
 118         /* enable TC0 */
 119         writel_relaxed(BM_C0_EN, priv.base + HW_TCR + SET_REG);
 120         return 0;
 121 }
 122
 123 static inline void __asm9260_timer_shutdown(struct clock_event_device *evt)
 124 {
 125         /* stop timer0 */
 126         writel_relaxed(BM_C0_EN, priv.base + HW_TCR + CLR_REG);
 127 }
 128
 129 static int asm9260_timer_shutdown(struct clock_event_device *evt)
 130 {
 131         __asm9260_timer_shutdown(evt);
 132         return 0;
 133 }
 134
 135 static int asm9260_timer_set_oneshot(struct clock_event_device *evt)
 136 {
 137         __asm9260_timer_shutdown(evt);
 138
 139         /* enable reset and stop on match */
 140         writel_relaxed(BM_MCR_RES_EN(0) | BM_MCR_STOP_EN(0),
 141                        priv.base + HW_MCR + SET_REG);
 142         return 0;
 143 }
 144
 145 static int asm9260_timer_set_periodic(struct clock_event_device *evt)
 146 {
 147         __asm9260_timer_shutdown(evt);
 148
 149         /* disable reset and stop on match */
 150         writel_relaxed(BM_MCR_RES_EN(0) | BM_MCR_STOP_EN(0),
 151                        priv.base + HW_MCR + CLR_REG);
 152         /* configure match count for TC0 */
 153         writel_relaxed(priv.ticks_per_jiffy, priv.base + HW_MR0);
 154         /* enable TC0 */
 155         writel_relaxed(BM_C0_EN, priv.base + HW_TCR + SET_REG);
 156         return 0;
 157 }
 158
 159 static struct clock_event_device event_dev = {
 160         .name                   = DRIVER_NAME,
 161         .rating                 = 200,
 162         .features               = CLOCK_EVT_FEAT_PERIODIC |
 163                                   CLOCK_EVT_FEAT_ONESHOT,
 164         .set_next_event         = asm9260_timer_set_next_event,
 165         .set_state_shutdown     = asm9260_timer_shutdown,
 166         .set_state_periodic     = asm9260_timer_set_periodic,
 167         .set_state_oneshot      = asm9260_timer_set_oneshot,
 168         .tick_resume            = asm9260_timer_shutdown,
 169 };
 170
 171 static irqreturn_t asm9260_timer_interrupt(int irq, void *dev_id)
 172 {
 173         struct clock_event_device *evt = dev_id;
 174
 175         evt->event_handler(evt);
 176
 177         writel_relaxed(BM_IR_MR0, priv.base + HW_IR);
 178
 179         return IRQ_HANDLED;
 180 }
 181
 182 /*
 183  * ---------------------------------------------------------------------------
 184  * Timer initialization
 185  * ---------------------------------------------------------------------------
 186  */
 187 static int __init asm9260_timer_init(struct device_node *np)
 188 {
 189         int irq;
 190         struct clk *clk;
 191         int ret;
 192         unsigned long rate;
 193
 194         priv.base = of_io_request_and_map(np, 0, np->name);
 195         if (IS_ERR(priv.base)) {
 196                 pr_err("%s: unable to map resource", np->name);
 197                 return PTR_ERR(priv.base);
 198         }
 199
 200         clk = of_clk_get(np, 0);
 201
 202         ret = clk_prepare_enable(clk);
 203         if (ret) {
 204                 pr_err("Failed to enable clk!\n");
 205                 return ret;
 206         }
 207
 208         irq = irq_of_parse_and_map(np, 0);
 209         ret = request_irq(irq, asm9260_timer_interrupt, IRQF_TIMER,
 210                         DRIVER_NAME, &event_dev);
 211         if (ret) {
 212                 pr_err("Failed to setup irq!\n");
 213                 return ret;
 214         }
 215
 216         /* set all timers for count-up */
 217         writel_relaxed(BM_DIR_DEFAULT, priv.base + HW_DIR);
 218         /* disable divider */
 219         writel_relaxed(BM_PR_DISABLE, priv.base + HW_PR);
 220         /* make sure all timers use every rising PCLK edge. */
 221         writel_relaxed(BM_CTCR_DEFAULT, priv.base + HW_CTCR);
 222         /* enable interrupt for TC0 and clean setting for all other lines */
 223         writel_relaxed(BM_MCR_INT_EN(0) , priv.base + HW_MCR);
 224
 225         rate = clk_get_rate(clk);
 226         clocksource_mmio_init(priv.base + HW_TC1, DRIVER_NAME, rate,
 227                         200, 32, clocksource_mmio_readl_up);
 228
 229         /* Seems like we can't use counter without match register even if
 230          * actions for MR are disabled. So, set MR to max value. */
 231         writel_relaxed(0xffffffff, priv.base + HW_MR1);
 232         /* enable TC1 */
 233         writel_relaxed(BM_C1_EN, priv.base + HW_TCR + SET_REG);
 234
 235         priv.ticks_per_jiffy = DIV_ROUND_CLOSEST(rate, HZ);
 236         event_dev.cpumask = cpumask_of(0);
 237         clockevents_config_and_register(&event_dev, rate, 0x2c00, 0xfffffffe);
 238
 239         return 0;
 240 }
 241 CLOCKSOURCE_OF_DECLARE(asm9260_timer, "alphascale,asm9260-timer",
 242                 asm9260_timer_init);