1 files changed, 148 insertions, 0 deletions
diff --git a/arch/mips/lasat/at93c.c b/arch/mips/lasat/at93c.c
new file mode 100644
index 000000000..f895fe94b
--- /dev/null
+++ b/arch/mips/lasat/at93c.c
@@ -0,0 +1,148 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Atmel AT93C46 serial eeprom driver
+ *
+ * Brian Murphy <brian.murphy@eicon.com>
+ *
+ */
+#include <linux/kernel.h>
+#include <linux/delay.h>
+#include <asm/lasat/lasat.h>
+
+#include "at93c.h"
+
+#define AT93C_ADDR_SHIFT	7
+#define AT93C_ADDR_MAX		((1 << AT93C_ADDR_SHIFT) - 1)
+#define AT93C_RCMD		(0x6 << AT93C_ADDR_SHIFT)
+#define AT93C_WCMD		(0x5 << AT93C_ADDR_SHIFT)
+#define AT93C_WENCMD		0x260
+#define AT93C_WDSCMD		0x200
+
+struct at93c_defs *at93c;
+
+static void at93c_reg_write(u32 val)
+{
+	*at93c->reg = val;
+}
+
+static u32 at93c_reg_read(void)
+{
+	u32 tmp = *at93c->reg;
+	return tmp;
+}
+
+static u32 at93c_datareg_read(void)
+{
+	u32 tmp = *at93c->rdata_reg;
+	return tmp;
+}
+
+static void at93c_cycle_clk(u32 data)
+{
+	at93c_reg_write(data | at93c->clk);
+	lasat_ndelay(250);
+	at93c_reg_write(data & ~at93c->clk);
+	lasat_ndelay(250);
+}
+
+static void at93c_write_databit(u8 bit)
+{
+	u32 data = at93c_reg_read();
+	if (bit)
+		data |= 1 << at93c->wdata_shift;
+	else
+		data &= ~(1 << at93c->wdata_shift);
+
+	at93c_reg_write(data);
+	lasat_ndelay(100);
+	at93c_cycle_clk(data);
+}
+
+static unsigned int at93c_read_databit(void)
+{
+	u32 data;
+
+	at93c_cycle_clk(at93c_reg_read());
+	data = (at93c_datareg_read() >> at93c->rdata_shift) & 1;
+	return data;
+}
+
+static u8 at93c_read_byte(void)
+{
+	int i;
+	u8 data = 0;
+
+	for (i = 0; i <= 7; i++) {
+		data <<= 1;
+		data |= at93c_read_databit();
+	}
+	return data;
+}
+
+static void at93c_write_bits(u32 data, int size)
+{
+	int i;
+	int shift = size - 1;
+	u32 mask = (1 << shift);
+
+	for (i = 0; i < size; i++) {
+		at93c_write_databit((data & mask) >> shift);
+		data <<= 1;
+	}
+}
+
+static void at93c_init_op(void)
+{
+	at93c_reg_write((at93c_reg_read() | at93c->cs) &
+			~at93c->clk & ~(1 << at93c->rdata_shift));
+	lasat_ndelay(50);
+}
+
+static void at93c_end_op(void)
+{
+	at93c_reg_write(at93c_reg_read() & ~at93c->cs);
+	lasat_ndelay(250);
+}
+
+static void at93c_wait(void)
+{
+	at93c_init_op();
+	while (!at93c_read_databit())
+		;
+	at93c_end_op();
+};
+
+static void at93c_disable_wp(void)
+{
+	at93c_init_op();
+	at93c_write_bits(AT93C_WENCMD, 10);
+	at93c_end_op();
+}
+
+static void at93c_enable_wp(void)
+{
+	at93c_init_op();
+	at93c_write_bits(AT93C_WDSCMD, 10);
+	at93c_end_op();
+}
+
+u8 at93c_read(u8 addr)
+{
+	u8 byte;
+	at93c_init_op();
+	at93c_write_bits((addr & AT93C_ADDR_MAX)|AT93C_RCMD, 10);
+	byte = at93c_read_byte();
+	at93c_end_op();
+	return byte;
+}
+
+void at93c_write(u8 addr, u8 data)
+{
+	at93c_disable_wp();
+	at93c_init_op();
+	at93c_write_bits((addr & AT93C_ADDR_MAX)|AT93C_WCMD, 10);
+	at93c_write_bits(data, 8);
+	at93c_end_op();
+	at93c_wait();
+	at93c_enable_wp();
+}