1 /* 2 * sysirq_mask.c - System-interrupt masking 3 * 4 * Copyright (C) 2013 Johan Hovold <jhovold@gmail.com> 5 * 6 * Functions to disable system interrupts from backup-powered peripherals. 7 * 8 * The RTC and RTT-peripherals are generally powered by backup power (VDDBU) 9 * and are not reset on wake-up, user, watchdog or software reset. This means 10 * that their interrupts may be enabled during early boot (e.g. after a user 11 * reset). 12 * 13 * As the RTC and RTT share the system-interrupt line with the PIT, an 14 * interrupt occurring before a handler has been installed would lead to the 15 * system interrupt being disabled and prevent the system from booting. 16 * 17 * This program is free software; you can redistribute it and/or modify 18 * it under the terms of the GNU General Public License as published by 19 * the Free Software Foundation; either version 2 of the License, or 20 * (at your option) any later version. 21 */ 22 23 #include <linux/io.h> 24 #include <mach/at91_rtt.h> 25 26 #include "generic.h" 27 28 #define AT91_RTC_IDR 0x24 /* Interrupt Disable Register */ 29 #define AT91_RTC_IMR 0x28 /* Interrupt Mask Register */ 30 #define AT91_RTC_IRQ_MASK 0x1f /* Available IRQs mask */ 31 at91_sysirq_mask_rtc(u32 rtc_base)32void __init at91_sysirq_mask_rtc(u32 rtc_base) 33 { 34 void __iomem *base; 35 36 base = ioremap(rtc_base, 64); 37 if (!base) 38 return; 39 40 /* 41 * sam9x5 SoCs have the following errata: 42 * "RTC: Interrupt Mask Register cannot be used 43 * Interrupt Mask Register read always returns 0." 44 * 45 * Hence we're not relying on IMR values to disable 46 * interrupts. 47 */ 48 writel_relaxed(AT91_RTC_IRQ_MASK, base + AT91_RTC_IDR); 49 (void)readl_relaxed(base + AT91_RTC_IMR); /* flush */ 50 51 iounmap(base); 52 } 53 at91_sysirq_mask_rtt(u32 rtt_base)54void __init at91_sysirq_mask_rtt(u32 rtt_base) 55 { 56 void __iomem *base; 57 void __iomem *reg; 58 u32 mode; 59 60 base = ioremap(rtt_base, 16); 61 if (!base) 62 return; 63 64 reg = base + AT91_RTT_MR; 65 66 mode = readl_relaxed(reg); 67 if (mode & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN)) { 68 pr_info("AT91: Disabling rtt irq\n"); 69 mode &= ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN); 70 writel_relaxed(mode, reg); 71 (void)readl_relaxed(reg); /* flush */ 72 } 73 74 iounmap(base); 75 } 76