1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * memory mapped NVRAM 4 * 5 * (C) Copyright IBM Corp. 2005 6 * 7 * Authors : Utz Bacher <utz.bacher@de.ibm.com> 8 */ 9 10 #include <linux/fs.h> 11 #include <linux/init.h> 12 #include <linux/kernel.h> 13 #include <linux/of_address.h> 14 #include <linux/spinlock.h> 15 #include <linux/types.h> 16 17 #include <asm/machdep.h> 18 #include <asm/nvram.h> 19 20 static void __iomem *mmio_nvram_start; 21 static long mmio_nvram_len; 22 static DEFINE_SPINLOCK(mmio_nvram_lock); 23 24 static ssize_t mmio_nvram_read(char *buf, size_t count, loff_t *index) 25 { 26 unsigned long flags; 27 28 if (*index >= mmio_nvram_len) 29 return 0; 30 if (*index + count > mmio_nvram_len) 31 count = mmio_nvram_len - *index; 32 33 spin_lock_irqsave(&mmio_nvram_lock, flags); 34 35 memcpy_fromio(buf, mmio_nvram_start + *index, count); 36 37 spin_unlock_irqrestore(&mmio_nvram_lock, flags); 38 39 *index += count; 40 return count; 41 } 42 43 static unsigned char mmio_nvram_read_val(int addr) 44 { 45 unsigned long flags; 46 unsigned char val; 47 48 if (addr >= mmio_nvram_len) 49 return 0xff; 50 51 spin_lock_irqsave(&mmio_nvram_lock, flags); 52 53 val = ioread8(mmio_nvram_start + addr); 54 55 spin_unlock_irqrestore(&mmio_nvram_lock, flags); 56 57 return val; 58 } 59 60 static ssize_t mmio_nvram_write(char *buf, size_t count, loff_t *index) 61 { 62 unsigned long flags; 63 64 if (*index >= mmio_nvram_len) 65 return 0; 66 if (*index + count > mmio_nvram_len) 67 count = mmio_nvram_len - *index; 68 69 spin_lock_irqsave(&mmio_nvram_lock, flags); 70 71 memcpy_toio(mmio_nvram_start + *index, buf, count); 72 73 spin_unlock_irqrestore(&mmio_nvram_lock, flags); 74 75 *index += count; 76 return count; 77 } 78 79 static void mmio_nvram_write_val(int addr, unsigned char val) 80 { 81 unsigned long flags; 82 83 if (addr < mmio_nvram_len) { 84 spin_lock_irqsave(&mmio_nvram_lock, flags); 85 86 iowrite8(val, mmio_nvram_start + addr); 87 88 spin_unlock_irqrestore(&mmio_nvram_lock, flags); 89 } 90 } 91 92 static ssize_t mmio_nvram_get_size(void) 93 { 94 return mmio_nvram_len; 95 } 96 97 int __init mmio_nvram_init(void) 98 { 99 struct device_node *nvram_node; 100 unsigned long nvram_addr; 101 struct resource r; 102 int ret; 103 104 nvram_node = of_find_node_by_type(NULL, "nvram"); 105 if (!nvram_node) 106 nvram_node = of_find_compatible_node(NULL, NULL, "nvram"); 107 if (!nvram_node) { 108 printk(KERN_WARNING "nvram: no node found in device-tree\n"); 109 return -ENODEV; 110 } 111 112 ret = of_address_to_resource(nvram_node, 0, &r); 113 if (ret) { 114 printk(KERN_WARNING "nvram: failed to get address (err %d)\n", 115 ret); 116 goto out; 117 } 118 nvram_addr = r.start; 119 mmio_nvram_len = resource_size(&r); 120 if ( (!mmio_nvram_len) || (!nvram_addr) ) { 121 printk(KERN_WARNING "nvram: address or length is 0\n"); 122 ret = -EIO; 123 goto out; 124 } 125 126 mmio_nvram_start = ioremap(nvram_addr, mmio_nvram_len); 127 if (!mmio_nvram_start) { 128 printk(KERN_WARNING "nvram: failed to ioremap\n"); 129 ret = -ENOMEM; 130 goto out; 131 } 132 133 printk(KERN_INFO "mmio NVRAM, %luk at 0x%lx mapped to %p\n", 134 mmio_nvram_len >> 10, nvram_addr, mmio_nvram_start); 135 136 ppc_md.nvram_read_val = mmio_nvram_read_val; 137 ppc_md.nvram_write_val = mmio_nvram_write_val; 138 ppc_md.nvram_read = mmio_nvram_read; 139 ppc_md.nvram_write = mmio_nvram_write; 140 ppc_md.nvram_size = mmio_nvram_get_size; 141 142 out: 143 of_node_put(nvram_node); 144 return ret; 145 } 146