1 /* 2 * c 2001 PPC 64 Team, IBM Corp 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public License 6 * as published by the Free Software Foundation; either version 7 * 2 of the License, or (at your option) any later version. 8 * 9 * /dev/nvram driver for PPC 10 * 11 */ 12 13 #include <linux/kernel.h> 14 #include <linux/init.h> 15 #include <linux/slab.h> 16 #include <linux/spinlock.h> 17 #include <asm/uaccess.h> 18 #include <asm/prom.h> 19 #include <asm/machdep.h> 20 #include <asm/rtas.h> 21 #include "chrp.h" 22 23 static unsigned int nvram_size; 24 static unsigned char nvram_buf[4]; 25 static DEFINE_SPINLOCK(nvram_lock); 26 27 static unsigned char chrp_nvram_read(int addr) 28 { 29 unsigned int done; 30 unsigned long flags; 31 unsigned char ret; 32 33 if (addr >= nvram_size) { 34 printk(KERN_DEBUG "%s: read addr %d > nvram_size %u\n", 35 current->comm, addr, nvram_size); 36 return 0xff; 37 } 38 spin_lock_irqsave(&nvram_lock, flags); 39 if ((rtas_call(rtas_token("nvram-fetch"), 3, 2, &done, addr, 40 __pa(nvram_buf), 1) != 0) || 1 != done) 41 ret = 0xff; 42 else 43 ret = nvram_buf[0]; 44 spin_unlock_irqrestore(&nvram_lock, flags); 45 46 return ret; 47 } 48 49 static void chrp_nvram_write(int addr, unsigned char val) 50 { 51 unsigned int done; 52 unsigned long flags; 53 54 if (addr >= nvram_size) { 55 printk(KERN_DEBUG "%s: write addr %d > nvram_size %u\n", 56 current->comm, addr, nvram_size); 57 return; 58 } 59 spin_lock_irqsave(&nvram_lock, flags); 60 nvram_buf[0] = val; 61 if ((rtas_call(rtas_token("nvram-store"), 3, 2, &done, addr, 62 __pa(nvram_buf), 1) != 0) || 1 != done) 63 printk(KERN_DEBUG "rtas IO error storing 0x%02x at %d", val, addr); 64 spin_unlock_irqrestore(&nvram_lock, flags); 65 } 66 67 void __init chrp_nvram_init(void) 68 { 69 struct device_node *nvram; 70 const unsigned int *nbytes_p; 71 unsigned int proplen; 72 73 nvram = of_find_node_by_type(NULL, "nvram"); 74 if (nvram == NULL) 75 return; 76 77 nbytes_p = of_get_property(nvram, "#bytes", &proplen); 78 if (nbytes_p == NULL || proplen != sizeof(unsigned int)) 79 return; 80 81 nvram_size = *nbytes_p; 82 83 printk(KERN_INFO "CHRP nvram contains %u bytes\n", nvram_size); 84 of_node_put(nvram); 85 86 ppc_md.nvram_read_val = chrp_nvram_read; 87 ppc_md.nvram_write_val = chrp_nvram_write; 88 89 return; 90 } 91