1 files changed, 95 insertions, 0 deletions
diff --git a/arch/powerpc/platforms/chrp/nvram.c b/arch/powerpc/platforms/chrp/nvram.c
new file mode 100644
index 000000000..e820332b5
--- /dev/null
+++ b/arch/powerpc/platforms/chrp/nvram.c
@@ -0,0 +1,95 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  c 2001 PPC 64 Team, IBM Corp
+ *
+ * /dev/nvram driver for PPC
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/spinlock.h>
+#include <linux/uaccess.h>
+#include <asm/prom.h>
+#include <asm/machdep.h>
+#include <asm/rtas.h>
+#include "chrp.h"
+
+static unsigned int nvram_size;
+static unsigned char nvram_buf[4];
+static DEFINE_SPINLOCK(nvram_lock);
+
+static unsigned char chrp_nvram_read_val(int addr)
+{
+	unsigned int done;
+	unsigned long flags;
+	unsigned char ret;
+
+	if (addr >= nvram_size) {
+		printk(KERN_DEBUG "%s: read addr %d > nvram_size %u\n",
+		       current->comm, addr, nvram_size);
+		return 0xff;
+	}
+	spin_lock_irqsave(&nvram_lock, flags);
+	if ((rtas_call(rtas_token("nvram-fetch"), 3, 2, &done, addr,
+		       __pa(nvram_buf), 1) != 0) || 1 != done)
+		ret = 0xff;
+	else
+		ret = nvram_buf[0];
+	spin_unlock_irqrestore(&nvram_lock, flags);
+
+	return ret;
+}
+
+static void chrp_nvram_write_val(int addr, unsigned char val)
+{
+	unsigned int done;
+	unsigned long flags;
+
+	if (addr >= nvram_size) {
+		printk(KERN_DEBUG "%s: write addr %d > nvram_size %u\n",
+		       current->comm, addr, nvram_size);
+		return;
+	}
+	spin_lock_irqsave(&nvram_lock, flags);
+	nvram_buf[0] = val;
+	if ((rtas_call(rtas_token("nvram-store"), 3, 2, &done, addr,
+		       __pa(nvram_buf), 1) != 0) || 1 != done)
+		printk(KERN_DEBUG "rtas IO error storing 0x%02x at %d", val, addr);
+	spin_unlock_irqrestore(&nvram_lock, flags);
+}
+
+static ssize_t chrp_nvram_size(void)
+{
+	return nvram_size;
+}
+
+void __init chrp_nvram_init(void)
+{
+	struct device_node *nvram;
+	const __be32 *nbytes_p;
+	unsigned int proplen;
+
+	nvram = of_find_node_by_type(NULL, "nvram");
+	if (nvram == NULL)
+		return;
+
+	nbytes_p = of_get_property(nvram, "#bytes", &proplen);
+	if (nbytes_p == NULL || proplen != sizeof(unsigned int)) {
+		of_node_put(nvram);
+		return;
+	}
+
+	nvram_size = be32_to_cpup(nbytes_p);
+
+	printk(KERN_INFO "CHRP nvram contains %u bytes\n", nvram_size);
+	of_node_put(nvram);
+
+	ppc_md.nvram_read_val  = chrp_nvram_read_val;
+	ppc_md.nvram_write_val = chrp_nvram_write_val;
+	ppc_md.nvram_size      = chrp_nvram_size;
+
+	return;
+}
+
+MODULE_LICENSE("GPL v2");