1 /* leon_pmc.c: LEON Power-down cpu_idle() handler 2 * 3 * Copyright (C) 2011 Daniel Hellstrom (daniel@gaisler.com) Aeroflex Gaisler AB 4 */ 5 6 #include <linux/init.h> 7 #include <linux/pm.h> 8 9 #include <asm/leon_amba.h> 10 #include <asm/cpu_type.h> 11 #include <asm/leon.h> 12 #include <asm/processor.h> 13 14 /* List of Systems that need fixup instructions around power-down instruction */ 15 static unsigned int pmc_leon_fixup_ids[] = { 16 AEROFLEX_UT699, 17 GAISLER_GR712RC, 18 LEON4_NEXTREME1, 19 0 20 }; 21 22 static int pmc_leon_need_fixup(void) 23 { 24 unsigned int systemid = amba_system_id >> 16; 25 unsigned int *id; 26 27 id = &pmc_leon_fixup_ids[0]; 28 while (*id != 0) { 29 if (*id == systemid) 30 return 1; 31 id++; 32 } 33 34 return 0; 35 } 36 37 /* 38 * CPU idle callback function for systems that need some extra handling 39 * See .../arch/sparc/kernel/process.c 40 */ 41 static void pmc_leon_idle_fixup(void) 42 { 43 /* Prepare an address to a non-cachable region. APB is always 44 * none-cachable. One instruction is executed after the Sleep 45 * instruction, we make sure to read the bus and throw away the 46 * value by accessing a non-cachable area, also we make sure the 47 * MMU does not get a TLB miss here by using the MMU BYPASS ASI. 48 */ 49 register unsigned int address = (unsigned int)leon3_irqctrl_regs; 50 51 /* Interrupts need to be enabled to not hang the CPU */ 52 local_irq_enable(); 53 54 __asm__ __volatile__ ( 55 "wr %%g0, %%asr19\n" 56 "lda [%0] %1, %%g0\n" 57 : 58 : "r"(address), "i"(ASI_LEON_BYPASS)); 59 } 60 61 /* 62 * CPU idle callback function 63 * See .../arch/sparc/kernel/process.c 64 */ 65 static void pmc_leon_idle(void) 66 { 67 /* Interrupts need to be enabled to not hang the CPU */ 68 local_irq_enable(); 69 70 /* For systems without power-down, this will be no-op */ 71 __asm__ __volatile__ ("wr %g0, %asr19\n\t"); 72 } 73 74 /* Install LEON Power Down function */ 75 static int __init leon_pmc_install(void) 76 { 77 if (sparc_cpu_model == sparc_leon) { 78 /* Assign power management IDLE handler */ 79 if (pmc_leon_need_fixup()) 80 sparc_idle = pmc_leon_idle_fixup; 81 else 82 sparc_idle = pmc_leon_idle; 83 84 printk(KERN_INFO "leon: power management initialized\n"); 85 } 86 87 return 0; 88 } 89 90 /* This driver is not critical to the boot process, don't care 91 * if initialized late. 92 */ 93 late_initcall(leon_pmc_install); 94