1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * c 2001 PPC 64 Team, IBM Corp 4 * 5 * /dev/nvram driver for PPC 6 */ 7 8 #include <linux/kernel.h> 9 #include <linux/module.h> 10 #include <linux/init.h> 11 #include <linux/spinlock.h> 12 #include <linux/uaccess.h> 13 #include <asm/prom.h> 14 #include <asm/machdep.h> 15 #include <asm/rtas.h> 16 #include "chrp.h" 17 18 static unsigned int nvram_size; 19 static unsigned char nvram_buf[4]; 20 static DEFINE_SPINLOCK(nvram_lock); 21 22 static unsigned char chrp_nvram_read_val(int addr) 23 { 24 unsigned int done; 25 unsigned long flags; 26 unsigned char ret; 27 28 if (addr >= nvram_size) { 29 printk(KERN_DEBUG "%s: read addr %d > nvram_size %u\n", 30 current->comm, addr, nvram_size); 31 return 0xff; 32 } 33 spin_lock_irqsave(&nvram_lock, flags); 34 if ((rtas_call(rtas_token("nvram-fetch"), 3, 2, &done, addr, 35 __pa(nvram_buf), 1) != 0) || 1 != done) 36 ret = 0xff; 37 else 38 ret = nvram_buf[0]; 39 spin_unlock_irqrestore(&nvram_lock, flags); 40 41 return ret; 42 } 43 44 static void chrp_nvram_write_val(int addr, unsigned char val) 45 { 46 unsigned int done; 47 unsigned long flags; 48 49 if (addr >= nvram_size) { 50 printk(KERN_DEBUG "%s: write addr %d > nvram_size %u\n", 51 current->comm, addr, nvram_size); 52 return; 53 } 54 spin_lock_irqsave(&nvram_lock, flags); 55 nvram_buf[0] = val; 56 if ((rtas_call(rtas_token("nvram-store"), 3, 2, &done, addr, 57 __pa(nvram_buf), 1) != 0) || 1 != done) 58 printk(KERN_DEBUG "rtas IO error storing 0x%02x at %d", val, addr); 59 spin_unlock_irqrestore(&nvram_lock, flags); 60 } 61 62 static ssize_t chrp_nvram_size(void) 63 { 64 return nvram_size; 65 } 66 67 void __init chrp_nvram_init(void) 68 { 69 struct device_node *nvram; 70 const __be32 *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 of_node_put(nvram); 80 return; 81 } 82 83 nvram_size = be32_to_cpup(nbytes_p); 84 85 printk(KERN_INFO "CHRP nvram contains %u bytes\n", nvram_size); 86 of_node_put(nvram); 87 88 ppc_md.nvram_read_val = chrp_nvram_read_val; 89 ppc_md.nvram_write_val = chrp_nvram_write_val; 90 ppc_md.nvram_size = chrp_nvram_size; 91 92 return; 93 } 94 95 MODULE_LICENSE("GPL v2"); 96