1 /* 2 * Pistachio clocksource based on general-purpose timers 3 * 4 * Copyright (C) 2015 Imagination Technologies 5 * 6 * This file is subject to the terms and conditions of the GNU General Public 7 * License. See the file "COPYING" in the main directory of this archive 8 * for more details. 9 */ 10 11 #define pr_fmt(fmt) "%s: " fmt, __func__ 12 13 #include <linux/clk.h> 14 #include <linux/clocksource.h> 15 #include <linux/clockchips.h> 16 #include <linux/delay.h> 17 #include <linux/err.h> 18 #include <linux/init.h> 19 #include <linux/spinlock.h> 20 #include <linux/mfd/syscon.h> 21 #include <linux/of.h> 22 #include <linux/of_address.h> 23 #include <linux/platform_device.h> 24 #include <linux/regmap.h> 25 #include <linux/sched_clock.h> 26 #include <linux/time.h> 27 28 /* Top level reg */ 29 #define CR_TIMER_CTRL_CFG 0x00 30 #define TIMER_ME_GLOBAL BIT(0) 31 #define CR_TIMER_REV 0x10 32 33 /* Timer specific registers */ 34 #define TIMER_CFG 0x20 35 #define TIMER_ME_LOCAL BIT(0) 36 #define TIMER_RELOAD_VALUE 0x24 37 #define TIMER_CURRENT_VALUE 0x28 38 #define TIMER_CURRENT_OVERFLOW_VALUE 0x2C 39 #define TIMER_IRQ_STATUS 0x30 40 #define TIMER_IRQ_CLEAR 0x34 41 #define TIMER_IRQ_MASK 0x38 42 43 #define PERIP_TIMER_CONTROL 0x90 44 45 /* Timer specific configuration Values */ 46 #define RELOAD_VALUE 0xffffffff 47 48 struct pistachio_clocksource { 49 void __iomem *base; 50 raw_spinlock_t lock; 51 struct clocksource cs; 52 }; 53 54 static struct pistachio_clocksource pcs_gpt; 55 56 #define to_pistachio_clocksource(cs) \ 57 container_of(cs, struct pistachio_clocksource, cs) 58 59 static inline u32 gpt_readl(void __iomem *base, u32 offset, u32 gpt_id) 60 { 61 return readl(base + 0x20 * gpt_id + offset); 62 } 63 64 static inline void gpt_writel(void __iomem *base, u32 value, u32 offset, 65 u32 gpt_id) 66 { 67 writel(value, base + 0x20 * gpt_id + offset); 68 } 69 70 static u64 notrace 71 pistachio_clocksource_read_cycles(struct clocksource *cs) 72 { 73 struct pistachio_clocksource *pcs = to_pistachio_clocksource(cs); 74 u32 counter, overflow; 75 unsigned long flags; 76 77 /* 78 * The counter value is only refreshed after the overflow value is read. 79 * And they must be read in strict order, hence raw spin lock added. 80 */ 81 82 raw_spin_lock_irqsave(&pcs->lock, flags); 83 overflow = gpt_readl(pcs->base, TIMER_CURRENT_OVERFLOW_VALUE, 0); 84 counter = gpt_readl(pcs->base, TIMER_CURRENT_VALUE, 0); 85 raw_spin_unlock_irqrestore(&pcs->lock, flags); 86 87 return (u64)~counter; 88 } 89 90 static u64 notrace pistachio_read_sched_clock(void) 91 { 92 return pistachio_clocksource_read_cycles(&pcs_gpt.cs); 93 } 94 95 static void pistachio_clksrc_set_mode(struct clocksource *cs, int timeridx, 96 int enable) 97 { 98 struct pistachio_clocksource *pcs = to_pistachio_clocksource(cs); 99 u32 val; 100 101 val = gpt_readl(pcs->base, TIMER_CFG, timeridx); 102 if (enable) 103 val |= TIMER_ME_LOCAL; 104 else 105 val &= ~TIMER_ME_LOCAL; 106 107 gpt_writel(pcs->base, val, TIMER_CFG, timeridx); 108 } 109 110 static void pistachio_clksrc_enable(struct clocksource *cs, int timeridx) 111 { 112 struct pistachio_clocksource *pcs = to_pistachio_clocksource(cs); 113 114 /* Disable GPT local before loading reload value */ 115 pistachio_clksrc_set_mode(cs, timeridx, false); 116 gpt_writel(pcs->base, RELOAD_VALUE, TIMER_RELOAD_VALUE, timeridx); 117 pistachio_clksrc_set_mode(cs, timeridx, true); 118 } 119 120 static void pistachio_clksrc_disable(struct clocksource *cs, int timeridx) 121 { 122 /* Disable GPT local */ 123 pistachio_clksrc_set_mode(cs, timeridx, false); 124 } 125 126 static int pistachio_clocksource_enable(struct clocksource *cs) 127 { 128 pistachio_clksrc_enable(cs, 0); 129 return 0; 130 } 131 132 static void pistachio_clocksource_disable(struct clocksource *cs) 133 { 134 pistachio_clksrc_disable(cs, 0); 135 } 136 137 /* Desirable clock source for pistachio platform */ 138 static struct pistachio_clocksource pcs_gpt = { 139 .cs = { 140 .name = "gptimer", 141 .rating = 300, 142 .enable = pistachio_clocksource_enable, 143 .disable = pistachio_clocksource_disable, 144 .read = pistachio_clocksource_read_cycles, 145 .mask = CLOCKSOURCE_MASK(32), 146 .flags = CLOCK_SOURCE_IS_CONTINUOUS | 147 CLOCK_SOURCE_SUSPEND_NONSTOP, 148 }, 149 }; 150 151 static int __init pistachio_clksrc_of_init(struct device_node *node) 152 { 153 struct clk *sys_clk, *fast_clk; 154 struct regmap *periph_regs; 155 unsigned long rate; 156 int ret; 157 158 pcs_gpt.base = of_iomap(node, 0); 159 if (!pcs_gpt.base) { 160 pr_err("cannot iomap\n"); 161 return -ENXIO; 162 } 163 164 periph_regs = syscon_regmap_lookup_by_phandle(node, "img,cr-periph"); 165 if (IS_ERR(periph_regs)) { 166 pr_err("cannot get peripheral regmap (%ld)\n", 167 PTR_ERR(periph_regs)); 168 return PTR_ERR(periph_regs); 169 } 170 171 /* Switch to using the fast counter clock */ 172 ret = regmap_update_bits(periph_regs, PERIP_TIMER_CONTROL, 173 0xf, 0x0); 174 if (ret) 175 return ret; 176 177 sys_clk = of_clk_get_by_name(node, "sys"); 178 if (IS_ERR(sys_clk)) { 179 pr_err("clock get failed (%ld)\n", PTR_ERR(sys_clk)); 180 return PTR_ERR(sys_clk); 181 } 182 183 fast_clk = of_clk_get_by_name(node, "fast"); 184 if (IS_ERR(fast_clk)) { 185 pr_err("clock get failed (%lu)\n", PTR_ERR(fast_clk)); 186 return PTR_ERR(fast_clk); 187 } 188 189 ret = clk_prepare_enable(sys_clk); 190 if (ret < 0) { 191 pr_err("failed to enable clock (%d)\n", ret); 192 return ret; 193 } 194 195 ret = clk_prepare_enable(fast_clk); 196 if (ret < 0) { 197 pr_err("failed to enable clock (%d)\n", ret); 198 clk_disable_unprepare(sys_clk); 199 return ret; 200 } 201 202 rate = clk_get_rate(fast_clk); 203 204 /* Disable irq's for clocksource usage */ 205 gpt_writel(pcs_gpt.base, 0, TIMER_IRQ_MASK, 0); 206 gpt_writel(pcs_gpt.base, 0, TIMER_IRQ_MASK, 1); 207 gpt_writel(pcs_gpt.base, 0, TIMER_IRQ_MASK, 2); 208 gpt_writel(pcs_gpt.base, 0, TIMER_IRQ_MASK, 3); 209 210 /* Enable timer block */ 211 writel(TIMER_ME_GLOBAL, pcs_gpt.base); 212 213 raw_spin_lock_init(&pcs_gpt.lock); 214 sched_clock_register(pistachio_read_sched_clock, 32, rate); 215 return clocksource_register_hz(&pcs_gpt.cs, rate); 216 } 217 TIMER_OF_DECLARE(pistachio_gptimer, "img,pistachio-gptimer", 218 pistachio_clksrc_of_init); 219