1 /* 2 * (C) Copyright 2008 - 2013 Tensilica Inc. 3 * 4 * SPDX-License-Identifier: GPL-2.0+ 5 */ 6 7 #include <common.h> 8 #include <asm/global_data.h> 9 #include <linux/stringify.h> 10 11 DECLARE_GLOBAL_DATA_PTR; 12 13 #if XCHAL_HAVE_CCOUNT 14 static ulong get_ccount(void) 15 { 16 ulong ccount; 17 asm volatile ("rsr %0,"__stringify(CCOUNT) : "=a" (ccount)); 18 return ccount; 19 } 20 #else 21 static ulong fake_ccount; 22 #define get_ccount() fake_ccount 23 #endif 24 25 static void delay_cycles(unsigned cycles) 26 { 27 #if XCHAL_HAVE_CCOUNT 28 unsigned expiry = get_ccount() + cycles; 29 while ((signed)(expiry - get_ccount()) > 0) 30 ; 31 #else 32 #warning "Without Xtensa timer option, timing will not be accurate." 33 34 /* 35 * Approximate the cycle count by a loop iteration count. 36 * This is highly dependent on config and optimization. 37 */ 38 39 volatile unsigned i; 40 for (i = cycles >> 4U; i > 0; --i) 41 ; 42 fake_ccount += cycles; 43 #endif 44 } 45 46 /* 47 * Delay (busy-wait) for a number of microseconds. 48 */ 49 50 void __udelay(unsigned long usec) 51 { 52 ulong lo, hi, i; 53 ulong mhz = CONFIG_SYS_CLK_FREQ / 1000000; 54 55 /* Scale to support full 32-bit usec range */ 56 57 lo = usec & ((1<<22)-1); 58 hi = usec >> 22UL; 59 for (i = 0; i < hi; ++i) 60 delay_cycles(mhz << 22); 61 delay_cycles(mhz * lo); 62 } 63 64 65 /* 66 * Return the elapsed time (ticks) since 'base'. 67 */ 68 69 ulong get_timer(ulong base) 70 { 71 /* Don't tie up a timer; use cycle counter if available (or fake it) */ 72 73 #if XCHAL_HAVE_CCOUNT 74 register ulong ccount; 75 __asm__ volatile ("rsr %0, CCOUNT" : "=a"(ccount)); 76 return ccount / (CONFIG_SYS_CLK_FREQ / CONFIG_SYS_HZ) - base; 77 #else 78 /* 79 * Add at least the overhead of this call (in cycles). 80 * Avoids hanging in case caller doesn't use udelay(). 81 * Note that functions that don't call udelay() (such as 82 * the "sleep" command) will not get a significant delay 83 * because there is no time reference. 84 */ 85 86 fake_ccount += 20; 87 return fake_ccount / (CONFIG_SYS_CLK_FREQ / CONFIG_SYS_HZ) - base; 88 #endif 89 } 90 91 92 /* 93 * This function is derived from ARM/PowerPC code (read timebase as long long). 94 * On Xtensa it just returns the timer value. 95 */ 96 unsigned long long get_ticks(void) 97 { 98 return get_timer(0); 99 } 100 101 /* 102 * This function is derived from ARM/PowerPC code (timebase clock frequency). 103 * On Xtensa it returns the number of timer ticks per second. 104 */ 105 ulong get_tbclk(void) 106 { 107 ulong tbclk; 108 109 tbclk = CONFIG_SYS_HZ; 110 return tbclk; 111 } 112 113 #if XCHAL_HAVE_CCOUNT 114 unsigned long timer_get_us(void) 115 { 116 unsigned long ccount; 117 118 __asm__ volatile ("rsr %0, CCOUNT" : "=a"(ccount)); 119 return ccount / (CONFIG_SYS_CLK_FREQ / 1000000); 120 } 121 #endif 122