1 /* 2 * This file is subject to the terms and conditions of the GNU General Public 3 * License. See the file "COPYING" in the main directory of this archive 4 * for more details. 5 * 6 * Copyright (C) 2007 by Ralf Baechle 7 */ 8 #include <linux/clocksource.h> 9 #include <linux/init.h> 10 11 #include <asm/time.h> 12 13 #include <asm/octeon/octeon.h> 14 #include <asm/octeon/cvmx-ipd-defs.h> 15 16 /* 17 * Set the current core's cvmcount counter to the value of the 18 * IPD_CLK_COUNT. We do this on all cores as they are brought 19 * on-line. This allows for a read from a local cpu register to 20 * access a synchronized counter. 21 * 22 */ 23 void octeon_init_cvmcount(void) 24 { 25 unsigned long flags; 26 unsigned loops = 2; 27 28 /* Clobber loops so GCC will not unroll the following while loop. */ 29 asm("" : "+r" (loops)); 30 31 local_irq_save(flags); 32 /* 33 * Loop several times so we are executing from the cache, 34 * which should give more deterministic timing. 35 */ 36 while (loops--) 37 write_c0_cvmcount(cvmx_read_csr(CVMX_IPD_CLK_COUNT)); 38 local_irq_restore(flags); 39 } 40 41 static cycle_t octeon_cvmcount_read(struct clocksource *cs) 42 { 43 return read_c0_cvmcount(); 44 } 45 46 static struct clocksource clocksource_mips = { 47 .name = "OCTEON_CVMCOUNT", 48 .read = octeon_cvmcount_read, 49 .mask = CLOCKSOURCE_MASK(64), 50 .flags = CLOCK_SOURCE_IS_CONTINUOUS, 51 }; 52 53 void __init plat_time_init(void) 54 { 55 clocksource_mips.rating = 300; 56 clocksource_set_clock(&clocksource_mips, mips_hpt_frequency); 57 clocksource_register(&clocksource_mips); 58 } 59