1 files changed, 122 insertions, 0 deletions
diff --git a/arch/mips/sgi-ip22/ip22-nvram.c b/arch/mips/sgi-ip22/ip22-nvram.c
new file mode 100644
index 000000000..e727ef519
--- /dev/null
+++ b/arch/mips/sgi-ip22/ip22-nvram.c
@@ -0,0 +1,122 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ip22-nvram.c: NVRAM and serial EEPROM handling.
+ *
+ * Copyright (C) 2003 Ladislav Michl (ladis@linux-mips.org)
+ */
+#include <linux/export.h>
+
+#include <asm/sgi/hpc3.h>
+#include <asm/sgi/ip22.h>
+
+/* Control opcode for serial eeprom  */
+#define EEPROM_READ	0xc000	/* serial memory read */
+#define EEPROM_WEN	0x9800	/* write enable before prog modes */
+#define EEPROM_WRITE	0xa000	/* serial memory write */
+#define EEPROM_WRALL	0x8800	/* write all registers */
+#define EEPROM_WDS	0x8000	/* disable all programming */
+#define EEPROM_PRREAD	0xc000	/* read protect register */
+#define EEPROM_PREN	0x9800	/* enable protect register mode */
+#define EEPROM_PRCLEAR	0xffff	/* clear protect register */
+#define EEPROM_PRWRITE	0xa000	/* write protect register */
+#define EEPROM_PRDS	0x8000	/* disable protect register, forever */
+
+#define EEPROM_EPROT	0x01	/* Protect register enable */
+#define EEPROM_CSEL	0x02	/* Chip select */
+#define EEPROM_ECLK	0x04	/* EEPROM clock */
+#define EEPROM_DATO	0x08	/* Data out */
+#define EEPROM_DATI	0x10	/* Data in */
+
+/* We need to use these functions early... */
+#define delay() ({						\
+	int x;							\
+	for (x=0; x<100000; x++) __asm__ __volatile__(""); })
+
+#define eeprom_cs_on(ptr) ({	\
+	__raw_writel(__raw_readl(ptr) & ~EEPROM_DATO, ptr);	\
+	__raw_writel(__raw_readl(ptr) & ~EEPROM_ECLK, ptr);	\
+	__raw_writel(__raw_readl(ptr) & ~EEPROM_EPROT, ptr);	\
+	delay();						\
+	__raw_writel(__raw_readl(ptr) | EEPROM_CSEL, ptr);	\
+	__raw_writel(__raw_readl(ptr) | EEPROM_ECLK, ptr); })
+
+
+#define eeprom_cs_off(ptr) ({	\
+	__raw_writel(__raw_readl(ptr) & ~EEPROM_ECLK, ptr);	\
+	__raw_writel(__raw_readl(ptr) & ~EEPROM_CSEL, ptr);	\
+	__raw_writel(__raw_readl(ptr) | EEPROM_EPROT, ptr);	\
+	__raw_writel(__raw_readl(ptr) | EEPROM_ECLK, ptr); })
+
+#define BITS_IN_COMMAND 11
+/*
+ * clock in the nvram command and the register number. For the
+ * national semiconductor nv ram chip the op code is 3 bits and
+ * the address is 6/8 bits.
+ */
+static inline void eeprom_cmd(unsigned int *ctrl, unsigned cmd, unsigned reg)
+{
+	unsigned short ser_cmd;
+	int i;
+
+	ser_cmd = cmd | (reg << (16 - BITS_IN_COMMAND));
+	for (i = 0; i < BITS_IN_COMMAND; i++) {
+		if (ser_cmd & (1<<15))	/* if high order bit set */
+			__raw_writel(__raw_readl(ctrl) | EEPROM_DATO, ctrl);
+		else
+			__raw_writel(__raw_readl(ctrl) & ~EEPROM_DATO, ctrl);
+		__raw_writel(__raw_readl(ctrl) & ~EEPROM_ECLK, ctrl);
+		delay();
+		__raw_writel(__raw_readl(ctrl) | EEPROM_ECLK, ctrl);
+		delay();
+		ser_cmd <<= 1;
+	}
+	/* see data sheet timing diagram */
+	__raw_writel(__raw_readl(ctrl) & ~EEPROM_DATO, ctrl);
+}
+
+unsigned short ip22_eeprom_read(unsigned int *ctrl, int reg)
+{
+	unsigned short res = 0;
+	int i;
+
+	__raw_writel(__raw_readl(ctrl) & ~EEPROM_EPROT, ctrl);
+	eeprom_cs_on(ctrl);
+	eeprom_cmd(ctrl, EEPROM_READ, reg);
+
+	/* clock the data ouf of serial mem */
+	for (i = 0; i < 16; i++) {
+		__raw_writel(__raw_readl(ctrl) & ~EEPROM_ECLK, ctrl);
+		delay();
+		__raw_writel(__raw_readl(ctrl) | EEPROM_ECLK, ctrl);
+		delay();
+		res <<= 1;
+		if (__raw_readl(ctrl) & EEPROM_DATI)
+			res |= 1;
+	}
+
+	eeprom_cs_off(ctrl);
+
+	return res;
+}
+
+EXPORT_SYMBOL(ip22_eeprom_read);
+
+/*
+ * Read specified register from main NVRAM
+ */
+unsigned short ip22_nvram_read(int reg)
+{
+	if (ip22_is_fullhouse())
+		/* IP22 (Indigo2 aka FullHouse) stores env variables into
+		 * 93CS56 Microwire Bus EEPROM 2048 Bit (128x16) */
+		return ip22_eeprom_read(&hpc3c0->eeprom, reg);
+	else {
+		unsigned short tmp;
+		/* IP24 (Indy aka Guiness) uses DS1386 8K version */
+		reg <<= 1;
+		tmp = hpc3c0->bbram[reg++] & 0xff;
+		return (tmp << 8) | (hpc3c0->bbram[reg] & 0xff);
+	}
+}
+
+EXPORT_SYMBOL(ip22_nvram_read);