1 /* 2 * PowerNV nvram code. 3 * 4 * Copyright 2011 IBM Corp. 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License 8 * as published by the Free Software Foundation; either version 9 * 2 of the License, or (at your option) any later version. 10 */ 11 12 #define DEBUG 13 14 #include <linux/kernel.h> 15 #include <linux/init.h> 16 #include <linux/of.h> 17 18 #include <asm/opal.h> 19 #include <asm/machdep.h> 20 21 static unsigned int nvram_size; 22 23 static ssize_t opal_nvram_size(void) 24 { 25 return nvram_size; 26 } 27 28 static ssize_t opal_nvram_read(char *buf, size_t count, loff_t *index) 29 { 30 s64 rc; 31 int off; 32 33 if (*index >= nvram_size) 34 return 0; 35 off = *index; 36 if ((off + count) > nvram_size) 37 count = nvram_size - off; 38 rc = opal_read_nvram(__pa(buf), count, off); 39 if (rc != OPAL_SUCCESS) 40 return -EIO; 41 *index += count; 42 return count; 43 } 44 45 static ssize_t opal_nvram_write(char *buf, size_t count, loff_t *index) 46 { 47 s64 rc = OPAL_BUSY; 48 int off; 49 50 if (*index >= nvram_size) 51 return 0; 52 off = *index; 53 if ((off + count) > nvram_size) 54 count = nvram_size - off; 55 56 while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) { 57 rc = opal_write_nvram(__pa(buf), count, off); 58 if (rc == OPAL_BUSY_EVENT) 59 opal_poll_events(NULL); 60 } 61 *index += count; 62 return count; 63 } 64 65 void __init opal_nvram_init(void) 66 { 67 struct device_node *np; 68 const __be32 *nbytes_p; 69 70 np = of_find_compatible_node(NULL, NULL, "ibm,opal-nvram"); 71 if (np == NULL) 72 return; 73 74 nbytes_p = of_get_property(np, "#bytes", NULL); 75 if (!nbytes_p) { 76 of_node_put(np); 77 return; 78 } 79 nvram_size = be32_to_cpup(nbytes_p); 80 81 pr_info("OPAL nvram setup, %u bytes\n", nvram_size); 82 of_node_put(np); 83 84 ppc_md.nvram_read = opal_nvram_read; 85 ppc_md.nvram_write = opal_nvram_write; 86 ppc_md.nvram_size = opal_nvram_size; 87 } 88 89