1 // SPDX-License-Identifier: GPL-2.0 2 /* leon_pmc.c: LEON Power-down cpu_idle() handler 3 * 4 * Copyright (C) 2011 Daniel Hellstrom (daniel@gaisler.com) Aeroflex Gaisler AB 5 */ 6 7 #include <linux/init.h> 8 #include <linux/pm.h> 9 10 #include <asm/leon_amba.h> 11 #include <asm/cpu_type.h> 12 #include <asm/leon.h> 13 #include <asm/processor.h> 14 15 /* List of Systems that need fixup instructions around power-down instruction */ 16 static unsigned int pmc_leon_fixup_ids[] = { 17 AEROFLEX_UT699, 18 GAISLER_GR712RC, 19 LEON4_NEXTREME1, 20 0 21 }; 22 23 static int pmc_leon_need_fixup(void) 24 { 25 unsigned int systemid = amba_system_id >> 16; 26 unsigned int *id; 27 28 id = &pmc_leon_fixup_ids[0]; 29 while (*id != 0) { 30 if (*id == systemid) 31 return 1; 32 id++; 33 } 34 35 return 0; 36 } 37 38 /* 39 * CPU idle callback function for systems that need some extra handling 40 * See .../arch/sparc/kernel/process.c 41 */ 42 static void pmc_leon_idle_fixup(void) 43 { 44 /* Prepare an address to a non-cachable region. APB is always 45 * none-cachable. One instruction is executed after the Sleep 46 * instruction, we make sure to read the bus and throw away the 47 * value by accessing a non-cachable area, also we make sure the 48 * MMU does not get a TLB miss here by using the MMU BYPASS ASI. 49 */ 50 register unsigned int address = (unsigned int)leon3_irqctrl_regs; 51 52 /* Interrupts need to be enabled to not hang the CPU */ 53 raw_local_irq_enable(); 54 55 __asm__ __volatile__ ( 56 "wr %%g0, %%asr19\n" 57 "lda [%0] %1, %%g0\n" 58 : 59 : "r"(address), "i"(ASI_LEON_BYPASS)); 60 61 raw_local_irq_disable(); 62 } 63 64 /* 65 * CPU idle callback function 66 * See .../arch/sparc/kernel/process.c 67 */ 68 static void pmc_leon_idle(void) 69 { 70 /* Interrupts need to be enabled to not hang the CPU */ 71 raw_local_irq_enable(); 72 73 /* For systems without power-down, this will be no-op */ 74 __asm__ __volatile__ ("wr %g0, %asr19\n\t"); 75 76 raw_local_irq_disable(); 77 } 78 79 /* Install LEON Power Down function */ 80 static int __init leon_pmc_install(void) 81 { 82 if (sparc_cpu_model == sparc_leon) { 83 /* Assign power management IDLE handler */ 84 if (pmc_leon_need_fixup()) 85 sparc_idle = pmc_leon_idle_fixup; 86 else 87 sparc_idle = pmc_leon_idle; 88 89 printk(KERN_INFO "leon: power management initialized\n"); 90 } 91 92 return 0; 93 } 94 95 /* This driver is not critical to the boot process, don't care 96 * if initialized late. 97 */ 98 late_initcall(leon_pmc_install); 99