platforms/chrp/nvram.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  *  c 2001 PPC 64 Team, IBM Corp
0004  *
0005  * /dev/nvram driver for PPC
0006  */
0007
0008 #include <linux/kernel.h>
0009 #include <linux/module.h>
0010 #include <linux/init.h>
0011 #include <linux/spinlock.h>
0012 #include <linux/uaccess.h>
0013 #include <linux/of.h>
0014 #include <asm/machdep.h>
0015 #include <asm/rtas.h>
0016 #include "chrp.h"
0017
0018 static unsigned int nvram_size;
0019 static unsigned char nvram_buf[4];
0020 static DEFINE_SPINLOCK(nvram_lock);
0021
0022 static unsigned char chrp_nvram_read_val(int addr)
0023 {
0024     unsigned int done;
0025     unsigned long flags;
0026     unsigned char ret;
0027
0028     if (addr >= nvram_size) {
0029         printk(KERN_DEBUG "%s: read addr %d > nvram_size %u\n",
0030                current->comm, addr, nvram_size);
0031         return 0xff;
0032     }
0033     spin_lock_irqsave(&nvram_lock, flags);
0034     if ((rtas_call(rtas_token("nvram-fetch"), 3, 2, &done, addr,
0035                __pa(nvram_buf), 1) != 0) || 1 != done)
0036         ret = 0xff;
0037     else
0038         ret = nvram_buf[0];
0039     spin_unlock_irqrestore(&nvram_lock, flags);
0040
0041     return ret;
0042 }
0043
0044 static void chrp_nvram_write_val(int addr, unsigned char val)
0045 {
0046     unsigned int done;
0047     unsigned long flags;
0048
0049     if (addr >= nvram_size) {
0050         printk(KERN_DEBUG "%s: write addr %d > nvram_size %u\n",
0051                current->comm, addr, nvram_size);
0052         return;
0053     }
0054     spin_lock_irqsave(&nvram_lock, flags);
0055     nvram_buf[0] = val;
0056     if ((rtas_call(rtas_token("nvram-store"), 3, 2, &done, addr,
0057                __pa(nvram_buf), 1) != 0) || 1 != done)
0058         printk(KERN_DEBUG "rtas IO error storing 0x%02x at %d", val, addr);
0059     spin_unlock_irqrestore(&nvram_lock, flags);
0060 }
0061
0062 static ssize_t chrp_nvram_size(void)
0063 {
0064     return nvram_size;
0065 }
0066
0067 void __init chrp_nvram_init(void)
0068 {
0069     struct device_node *nvram;
0070     const __be32 *nbytes_p;
0071     unsigned int proplen;
0072
0073     nvram = of_find_node_by_type(NULL, "nvram");
0074     if (nvram == NULL)
0075         return;
0076
0077     nbytes_p = of_get_property(nvram, "#bytes", &proplen);
0078     if (nbytes_p == NULL || proplen != sizeof(unsigned int)) {
0079         of_node_put(nvram);
0080         return;
0081     }
0082
0083     nvram_size = be32_to_cpup(nbytes_p);
0084
0085     printk(KERN_INFO "CHRP nvram contains %u bytes\n", nvram_size);
0086     of_node_put(nvram);
0087
0088     ppc_md.nvram_read_val  = chrp_nvram_read_val;
0089     ppc_md.nvram_write_val = chrp_nvram_write_val;
0090     ppc_md.nvram_size      = chrp_nvram_size;
0091
0092     return;
0093 }
0094
0095 MODULE_LICENSE("GPL v2");