drivers/clocksource/asm9260_timer.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (C) 2014 Oleksij Rempel <linux@rempel-privat.de>
   4  */
   5
   6 #include <linux/kernel.h>
   7 #include <linux/init.h>
   8 #include <linux/interrupt.h>
   9 #include <linux/sched.h>
  10 #include <linux/clk.h>
  11 #include <linux/clocksource.h>
  12 #include <linux/clockchips.h>
  13 #include <linux/io.h>
  14 #include <linux/of.h>
  15 #include <linux/of_address.h>
  16 #include <linux/of_irq.h>
  17 #include <linux/bitops.h>
  18
  19 #define DRIVER_NAME     "asm9260-timer"
  20
  21 /*
  22  * this device provide 4 offsets for each register:
  23  * 0x0 - plain read write mode
  24  * 0x4 - set mode, OR logic.
  25  * 0x8 - clr mode, XOR logic.
  26  * 0xc - togle mode.
  27  */
  28 #define SET_REG 4
  29 #define CLR_REG 8
  30
  31 #define HW_IR           0x0000 /* RW. Interrupt */
  32 #define BM_IR_CR0       BIT(4)
  33 #define BM_IR_MR3       BIT(3)
  34 #define BM_IR_MR2       BIT(2)
  35 #define BM_IR_MR1       BIT(1)
  36 #define BM_IR_MR0       BIT(0)
  37
  38 #define HW_TCR          0x0010 /* RW. Timer controller */
  39 /* BM_C*_RST
  40  * Timer Counter and the Prescale Counter are synchronously reset on the
  41  * next positive edge of PCLK. The counters remain reset until TCR[1] is
  42  * returned to zero. */
  43 #define BM_C3_RST       BIT(7)
  44 #define BM_C2_RST       BIT(6)
  45 #define BM_C1_RST       BIT(5)
  46 #define BM_C0_RST       BIT(4)
  47 /* BM_C*_EN
  48  * 1 - Timer Counter and Prescale Counter are enabled for counting
  49  * 0 - counters are disabled */
  50 #define BM_C3_EN        BIT(3)
  51 #define BM_C2_EN        BIT(2)
  52 #define BM_C1_EN        BIT(1)
  53 #define BM_C0_EN        BIT(0)
  54
  55 #define HW_DIR          0x0020 /* RW. Direction? */
  56 /* 00 - count up
  57  * 01 - count down
  58  * 10 - ?? 2^n/2 */
  59 #define BM_DIR_COUNT_UP         0
  60 #define BM_DIR_COUNT_DOWN       1
  61 #define BM_DIR0_SHIFT   0
  62 #define BM_DIR1_SHIFT   4
  63 #define BM_DIR2_SHIFT   8
  64 #define BM_DIR3_SHIFT   12
  65 #define BM_DIR_DEFAULT          (BM_DIR_COUNT_UP << BM_DIR0_SHIFT | \
  66                                  BM_DIR_COUNT_UP << BM_DIR1_SHIFT | \
  67                                  BM_DIR_COUNT_UP << BM_DIR2_SHIFT | \
  68                                  BM_DIR_COUNT_UP << BM_DIR3_SHIFT)
  69
  70 #define HW_TC0          0x0030 /* RO. Timer counter 0 */
  71 /* HW_TC*. Timer counter owerflow (0xffff.ffff to 0x0000.0000) do not generate
  72  * interrupt. This registers can be used to detect overflow */
  73 #define HW_TC1          0x0040
  74 #define HW_TC2          0x0050
  75 #define HW_TC3          0x0060
  76
  77 #define HW_PR           0x0070 /* RW. prescaler */
  78 #define BM_PR_DISABLE   0
  79 #define HW_PC           0x0080 /* RO. Prescaler counter */
  80 #define HW_MCR          0x0090 /* RW. Match control */
  81 /* enable interrupt on match */
  82 #define BM_MCR_INT_EN(n)        (1 << (n * 3 + 0))
  83 /* enable TC reset on match */
  84 #define BM_MCR_RES_EN(n)        (1 << (n * 3 + 1))
  85 /* enable stop TC on match */
  86 #define BM_MCR_STOP_EN(n)       (1 << (n * 3 + 2))
  87
  88 #define HW_MR0          0x00a0 /* RW. Match reg */
  89 #define HW_MR1          0x00b0
  90 #define HW_MR2          0x00C0
  91 #define HW_MR3          0x00D0
  92
  93 #define HW_CTCR         0x0180 /* Counter control */
  94 #define BM_CTCR0_SHIFT  0
  95 #define BM_CTCR1_SHIFT  2
  96 #define BM_CTCR2_SHIFT  4
  97 #define BM_CTCR3_SHIFT  6
  98 #define BM_CTCR_TM      0       /* Timer mode. Every rising PCLK edge. */
  99 #define BM_CTCR_DEFAULT (BM_CTCR_TM << BM_CTCR0_SHIFT | \
 100                          BM_CTCR_TM << BM_CTCR1_SHIFT | \
 101                          BM_CTCR_TM << BM_CTCR2_SHIFT | \
 102                          BM_CTCR_TM << BM_CTCR3_SHIFT)
 103
 104 static struct asm9260_timer_priv {
 105         void __iomem *base;
 106         unsigned long ticks_per_jiffy;
 107 } priv;
 108
 109 static int asm9260_timer_set_next_event(unsigned long delta,
 110                                          struct clock_event_device *evt)
 111 {
 112         /* configure match count for TC0 */
 113         writel_relaxed(delta, priv.base + HW_MR0);
 114         /* enable TC0 */
 115         writel_relaxed(BM_C0_EN, priv.base + HW_TCR + SET_REG);
 116         return 0;
 117 }
 118
 119 static inline void __asm9260_timer_shutdown(struct clock_event_device *evt)
 120 {
 121         /* stop timer0 */
 122         writel_relaxed(BM_C0_EN, priv.base + HW_TCR + CLR_REG);
 123 }
 124
 125 static int asm9260_timer_shutdown(struct clock_event_device *evt)
 126 {
 127         __asm9260_timer_shutdown(evt);
 128         return 0;
 129 }
 130
 131 static int asm9260_timer_set_oneshot(struct clock_event_device *evt)
 132 {
 133         __asm9260_timer_shutdown(evt);
 134
 135         /* enable reset and stop on match */
 136         writel_relaxed(BM_MCR_RES_EN(0) | BM_MCR_STOP_EN(0),
 137                        priv.base + HW_MCR + SET_REG);
 138         return 0;
 139 }
 140
 141 static int asm9260_timer_set_periodic(struct clock_event_device *evt)
 142 {
 143         __asm9260_timer_shutdown(evt);
 144
 145         /* disable reset and stop on match */
 146         writel_relaxed(BM_MCR_RES_EN(0) | BM_MCR_STOP_EN(0),
 147                        priv.base + HW_MCR + CLR_REG);
 148         /* configure match count for TC0 */
 149         writel_relaxed(priv.ticks_per_jiffy, priv.base + HW_MR0);
 150         /* enable TC0 */
 151         writel_relaxed(BM_C0_EN, priv.base + HW_TCR + SET_REG);
 152         return 0;
 153 }
 154
 155 static struct clock_event_device event_dev = {
 156         .name                   = DRIVER_NAME,
 157         .rating                 = 200,
 158         .features               = CLOCK_EVT_FEAT_PERIODIC |
 159                                   CLOCK_EVT_FEAT_ONESHOT,
 160         .set_next_event         = asm9260_timer_set_next_event,
 161         .set_state_shutdown     = asm9260_timer_shutdown,
 162         .set_state_periodic     = asm9260_timer_set_periodic,
 163         .set_state_oneshot      = asm9260_timer_set_oneshot,
 164         .tick_resume            = asm9260_timer_shutdown,
 165 };
 166
 167 static irqreturn_t asm9260_timer_interrupt(int irq, void *dev_id)
 168 {
 169         struct clock_event_device *evt = dev_id;
 170
 171         evt->event_handler(evt);
 172
 173         writel_relaxed(BM_IR_MR0, priv.base + HW_IR);
 174
 175         return IRQ_HANDLED;
 176 }
 177
 178 /*
 179  * ---------------------------------------------------------------------------
 180  * Timer initialization
 181  * ---------------------------------------------------------------------------
 182  */
 183 static int __init asm9260_timer_init(struct device_node *np)
 184 {
 185         int irq;
 186         struct clk *clk;
 187         int ret;
 188         unsigned long rate;
 189
 190         priv.base = of_io_request_and_map(np, 0, np->name);
 191         if (IS_ERR(priv.base)) {
 192                 pr_err("%pOFn: unable to map resource\n", np);
 193                 return PTR_ERR(priv.base);
 194         }
 195
 196         clk = of_clk_get(np, 0);
 197         if (IS_ERR(clk)) {
 198                 pr_err("Failed to get clk!\n");
 199                 return PTR_ERR(clk);
 200         }
 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 TIMER_OF_DECLARE(asm9260_timer, "alphascale,asm9260-timer",
 242                 asm9260_timer_init);