| Marek Vasut | 6e9a0a3 | 2011-11-08 23:18:08 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Freescale i.MX28 timer driver |
| 3 | * |
| 4 | * Copyright (C) 2011 Marek Vasut <marek.vasut@gmail.com> |
| 5 | * on behalf of DENX Software Engineering GmbH |
| 6 | * |
| 7 | * Based on code from LTIB: |
| 8 | * (C) Copyright 2009-2010 Freescale Semiconductor, Inc. |
| 9 | * |
| 10 | * See file CREDITS for list of people who contributed to this |
| 11 | * project. |
| 12 | * |
| 13 | * This program is free software; you can redistribute it and/or |
| 14 | * modify it under the terms of the GNU General Public License as |
| 15 | * published by the Free Software Foundation; either version 2 of |
| 16 | * the License, or (at your option) any later version. |
| 17 | * |
| 18 | * This program is distributed in the hope that it will be useful, |
| 19 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 20 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 21 | * GNU General Public License for more details. |
| 22 | * |
| 23 | * You should have received a copy of the GNU General Public License |
| 24 | * along with this program; if not, write to the Free Software |
| 25 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, |
| 26 | * MA 02111-1307 USA |
| 27 | */ |
| 28 | |
| 29 | #include <common.h> |
| 30 | #include <asm/io.h> |
| 31 | #include <asm/arch/imx-regs.h> |
| 32 | #include <asm/arch/sys_proto.h> |
| 33 | |
| 34 | /* Maximum fixed count */ |
| 35 | #define TIMER_LOAD_VAL 0xffffffff |
| 36 | |
| 37 | DECLARE_GLOBAL_DATA_PTR; |
| 38 | |
| 39 | #define timestamp (gd->tbl) |
| 40 | #define lastdec (gd->lastinc) |
| 41 | |
| 42 | /* |
| 43 | * This driver uses 1kHz clock source. |
| 44 | */ |
| 45 | #define MX28_INCREMENTER_HZ 1000 |
| 46 | |
| 47 | static inline unsigned long tick_to_time(unsigned long tick) |
| 48 | { |
| 49 | return tick / (MX28_INCREMENTER_HZ / CONFIG_SYS_HZ); |
| 50 | } |
| 51 | |
| 52 | static inline unsigned long time_to_tick(unsigned long time) |
| 53 | { |
| 54 | return time * (MX28_INCREMENTER_HZ / CONFIG_SYS_HZ); |
| 55 | } |
| 56 | |
| 57 | /* Calculate how many ticks happen in "us" microseconds */ |
| 58 | static inline unsigned long us_to_tick(unsigned long us) |
| 59 | { |
| 60 | return (us * MX28_INCREMENTER_HZ) / 1000000; |
| 61 | } |
| 62 | |
| 63 | int timer_init(void) |
| 64 | { |
| 65 | struct mx28_timrot_regs *timrot_regs = |
| 66 | (struct mx28_timrot_regs *)MXS_TIMROT_BASE; |
| 67 | |
| 68 | /* Reset Timers and Rotary Encoder module */ |
| 69 | mx28_reset_block(&timrot_regs->hw_timrot_rotctrl_reg); |
| 70 | |
| 71 | /* Set fixed_count to 0 */ |
| 72 | writel(0, &timrot_regs->hw_timrot_fixed_count0); |
| 73 | |
| 74 | /* Set UPDATE bit and 1Khz frequency */ |
| 75 | writel(TIMROT_TIMCTRLn_UPDATE | TIMROT_TIMCTRLn_RELOAD | |
| 76 | TIMROT_TIMCTRLn_SELECT_1KHZ_XTAL, |
| 77 | &timrot_regs->hw_timrot_timctrl0); |
| 78 | |
| 79 | /* Set fixed_count to maximal value */ |
| 80 | writel(TIMER_LOAD_VAL, &timrot_regs->hw_timrot_fixed_count0); |
| 81 | |
| 82 | return 0; |
| 83 | } |
| 84 | |
| 85 | ulong get_timer(ulong base) |
| 86 | { |
| 87 | struct mx28_timrot_regs *timrot_regs = |
| 88 | (struct mx28_timrot_regs *)MXS_TIMROT_BASE; |
| 89 | |
| 90 | /* Current tick value */ |
| 91 | uint32_t now = readl(&timrot_regs->hw_timrot_running_count0); |
| 92 | |
| 93 | if (lastdec >= now) { |
| 94 | /* |
| 95 | * normal mode (non roll) |
| 96 | * move stamp forward with absolut diff ticks |
| 97 | */ |
| 98 | timestamp += (lastdec - now); |
| 99 | } else { |
| 100 | /* we have rollover of decrementer */ |
| 101 | timestamp += (TIMER_LOAD_VAL - now) + lastdec; |
| 102 | |
| 103 | } |
| 104 | lastdec = now; |
| 105 | |
| 106 | return tick_to_time(timestamp) - base; |
| 107 | } |
| 108 | |
| 109 | /* We use the HW_DIGCTL_MICROSECONDS register for sub-millisecond timer. */ |
| 110 | #define MX28_HW_DIGCTL_MICROSECONDS 0x8001c0c0 |
| 111 | |
| 112 | void __udelay(unsigned long usec) |
| 113 | { |
| 114 | uint32_t old, new, incr; |
| 115 | uint32_t counter = 0; |
| 116 | |
| 117 | old = readl(MX28_HW_DIGCTL_MICROSECONDS); |
| 118 | |
| 119 | while (counter < usec) { |
| 120 | new = readl(MX28_HW_DIGCTL_MICROSECONDS); |
| 121 | |
| 122 | /* Check if the timer wrapped. */ |
| 123 | if (new < old) { |
| 124 | incr = 0xffffffff - old; |
| 125 | incr += new; |
| 126 | } else { |
| 127 | incr = new - old; |
| 128 | } |
| 129 | |
| 130 | /* |
| 131 | * Check if we are close to the maximum time and the counter |
| 132 | * would wrap if incremented. If that's the case, break out |
| 133 | * from the loop as the requested delay time passed. |
| 134 | */ |
| 135 | if (counter + incr < counter) |
| 136 | break; |
| 137 | |
| 138 | counter += incr; |
| 139 | old = new; |
| 140 | } |
| 141 | } |