drivers/clocksource/timer-ti-32k.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * timer-ti-32k.c - OMAP2 32k Timer Support
   4  *
   5  * Copyright (C) 2009 Nokia Corporation
   6  *
   7  * Update to use new clocksource/clockevent layers
   8  * Author: Kevin Hilman, MontaVista Software, Inc. <source@mvista.com>
   9  * Copyright (C) 2007 MontaVista Software, Inc.
  10  *
  11  * Original driver:
  12  * Copyright (C) 2005 Nokia Corporation
  13  * Author: Paul Mundt <paul.mundt@nokia.com>
  14  *         Juha Yrjölä <juha.yrjola@nokia.com>
  15  * OMAP Dual-mode timer framework support by Timo Teras
  16  *
  17  * Some parts based off of TI's 24xx code:
  18  *
  19  * Copyright (C) 2004-2009 Texas Instruments, Inc.
  20  *
  21  * Roughly modelled after the OMAP1 MPU timer code.
  22  * Added OMAP4 support - Santosh Shilimkar <santosh.shilimkar@ti.com>
  23  *
  24  * Copyright (C) 2015 Texas Instruments Incorporated - https://www.ti.com
  25  */
  26
  27 #include <linux/clk.h>
  28 #include <linux/init.h>
  29 #include <linux/time.h>
  30 #include <linux/sched_clock.h>
  31 #include <linux/clocksource.h>
  32 #include <linux/of.h>
  33 #include <linux/of_address.h>
  34
  35 /*
  36  * 32KHz clocksource ... always available, on pretty most chips except
  37  * OMAP 730 and 1510.  Other timers could be used as clocksources, with
  38  * higher resolution in free-running counter modes (e.g. 12 MHz xtal),
  39  * but systems won't necessarily want to spend resources that way.
  40  */
  41
  42 #define OMAP2_32KSYNCNT_REV_OFF         0x0
  43 #define OMAP2_32KSYNCNT_REV_SCHEME      (0x3 << 30)
  44 #define OMAP2_32KSYNCNT_CR_OFF_LOW      0x10
  45 #define OMAP2_32KSYNCNT_CR_OFF_HIGH     0x30
  46
  47 struct ti_32k {
  48         void __iomem            *base;
  49         void __iomem            *counter;
  50         struct clocksource      cs;
  51 };
  52
  53 static inline struct ti_32k *to_ti_32k(struct clocksource *cs)
  54 {
  55         return container_of(cs, struct ti_32k, cs);
  56 }
  57
  58 static u64 notrace ti_32k_read_cycles(struct clocksource *cs)
  59 {
  60         struct ti_32k *ti = to_ti_32k(cs);
  61
  62         return (u64)readl_relaxed(ti->counter);
  63 }
  64
  65 static struct ti_32k ti_32k_timer = {
  66         .cs = {
  67                 .name           = "32k_counter",
  68                 .rating         = 250,
  69                 .read           = ti_32k_read_cycles,
  70                 .mask           = CLOCKSOURCE_MASK(32),
  71                 .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  72         },
  73 };
  74
  75 static u64 notrace omap_32k_read_sched_clock(void)
  76 {
  77         return ti_32k_read_cycles(&ti_32k_timer.cs);
  78 }
  79
  80 static void __init ti_32k_timer_enable_clock(struct device_node *np,
  81                                              const char *name)
  82 {
  83         struct clk *clock;
  84         int error;
  85
  86         clock = of_clk_get_by_name(np->parent, name);
  87         if (IS_ERR(clock)) {
  88                 /* Only some SoCs have a separate interface clock */
  89                 if (PTR_ERR(clock) == -EINVAL && !strncmp("ick", name, 3))
  90                         return;
  91
  92                 pr_warn("%s: could not get clock %s %li\n",
  93                         __func__, name, PTR_ERR(clock));
  94                 return;
  95         }
  96
  97         error = clk_prepare_enable(clock);
  98         if (error) {
  99                 pr_warn("%s: could not enable %s: %i\n",
 100                         __func__, name, error);
 101                 return;
 102         }
 103 }
 104
 105 static void __init ti_32k_timer_module_init(struct device_node *np,
 106                                             void __iomem *base)
 107 {
 108         void __iomem *sysc = base + 4;
 109
 110         if (!of_device_is_compatible(np->parent, "ti,sysc"))
 111                 return;
 112
 113         ti_32k_timer_enable_clock(np, "fck");
 114         ti_32k_timer_enable_clock(np, "ick");
 115
 116         /*
 117          * Force idle module as wkup domain is active with MPU.
 118          * No need to tag the module disabled for ti-sysc probe.
 119          */
 120         writel_relaxed(0, sysc);
 121 }
 122
 123 static int __init ti_32k_timer_init(struct device_node *np)
 124 {
 125         int ret;
 126
 127         ti_32k_timer.base = of_iomap(np, 0);
 128         if (!ti_32k_timer.base) {
 129                 pr_err("Can't ioremap 32k timer base\n");
 130                 return -ENXIO;
 131         }
 132
 133         if (!of_machine_is_compatible("ti,am43"))
 134                 ti_32k_timer.cs.flags |= CLOCK_SOURCE_SUSPEND_NONSTOP;
 135
 136         ti_32k_timer.counter = ti_32k_timer.base;
 137         ti_32k_timer_module_init(np, ti_32k_timer.base);
 138
 139         /*
 140          * 32k sync Counter IP register offsets vary between the highlander
 141          * version and the legacy ones.
 142          *
 143          * The 'SCHEME' bits(30-31) of the revision register is used to identify
 144          * the version.
 145          */
 146         if (readl_relaxed(ti_32k_timer.base + OMAP2_32KSYNCNT_REV_OFF) &
 147                         OMAP2_32KSYNCNT_REV_SCHEME)
 148                 ti_32k_timer.counter += OMAP2_32KSYNCNT_CR_OFF_HIGH;
 149         else
 150                 ti_32k_timer.counter += OMAP2_32KSYNCNT_CR_OFF_LOW;
 151
 152         pr_info("OMAP clocksource: 32k_counter at 32768 Hz\n");
 153
 154         ret = clocksource_register_hz(&ti_32k_timer.cs, 32768);
 155         if (ret) {
 156                 pr_err("32k_counter: can't register clocksource\n");
 157                 return ret;
 158         }
 159
 160         sched_clock_register(omap_32k_read_sched_clock, 32, 32768);
 161
 162         return 0;
 163 }
 164 TIMER_OF_DECLARE(ti_32k_timer, "ti,omap-counter32k",
 165                 ti_32k_timer_init);