rtd2132: Add driver for Realtek RTD2132 LVDS bridge

This driver allows the mainboard to enable spread spectrum
clocking at 0.5%, 1.0%, and 1.5% with devicetree settings.

Change-Id: I59c61e67aa8e951fd9904ad951deb6d0ba29669e
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/61894
Reviewed-on: http://review.coreboot.org/4365
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>
Tested-by: build bot (Jenkins)

4 files changed, 182 insertions, 0 deletions

diff --git a/src/drivers/i2c/rtd2132/Kconfig b/src/drivers/i2c/rtd2132/Kconfig
new file mode 100644
index 0000000000..f76b14ff23
--- /dev/null
+++ b/src/drivers/i2c/rtd2132/Kconfig
@@ -0,0 +1,5 @@
+config DRIVERS_I2C_RTD2132
+	bool
+	default n
+	help
+	  Enable support for Realtek RTD2132 DisplayPort to LVDS bridge chip.
diff --git a/src/drivers/i2c/rtd2132/Makefile.inc b/src/drivers/i2c/rtd2132/Makefile.inc
new file mode 100644
index 0000000000..4974a479ce
--- /dev/null
+++ b/src/drivers/i2c/rtd2132/Makefile.inc
@@ -0,0 +1 @@
+ramstage-$(CONFIG_DRIVERS_I2C_RTD2132) += rtd2132.c
diff --git a/src/drivers/i2c/rtd2132/chip.h b/src/drivers/i2c/rtd2132/chip.h
new file mode 100644
index 0000000000..34ae91a3fe
--- /dev/null
+++ b/src/drivers/i2c/rtd2132/chip.h
@@ -0,0 +1,29 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2013 Google Inc.  All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA, 02110-1301 USA
+ */
+
+struct drivers_i2c_rtd2132_config {
+	/*
+	 * LVDS Spread Spectrum Clock
+	 *  0x00 = DISABLED
+	 *  0x05 = 0.5%
+	 *  0x10 = 1.0%
+	 *  0x15 = 1.5%
+	 */
+	u8 sscg_percent;
+};
diff --git a/src/drivers/i2c/rtd2132/rtd2132.c b/src/drivers/i2c/rtd2132/rtd2132.c
new file mode 100644
index 0000000000..a3470b0453
--- /dev/null
+++ b/src/drivers/i2c/rtd2132/rtd2132.c
@@ -0,0 +1,147 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2013 Google Inc.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA, 02110-1301 USA
+ */
+
+#include <console/console.h>
+#include <delay.h>
+#include <device/device.h>
+#include <device/smbus.h>
+#include <device/pci.h>
+#include "chip.h"
+
+/* Chip commands */
+#define RTD2132_COMMAND			0x01
+#define RTD2132_DATA			0x00
+#define RTD2132_FIRMWARE		0x80
+#define  RTD2132_FIRMWARE_START		0x00
+#define  RTD2132_FIRMWARE_STOP		0x01
+
+/* Spread spectrum configuration */
+#define RTD2132_COMMAND_SSCG_CONFIG_0	0x39
+#define  RTD2132_SSCG_ENABLE		0xa0
+#define  RTD2132_SSCG_DISABLE		0x20
+#define RTD2132_COMMAND_SSCG_CONFIG_1	0x3a
+#define  RTD2132_SSCG_CONFIG_DISABLED	0x01	/* DISABLED */
+#define  RTD2132_SSCG_CONFIG_0_5	0x07	/* 0.5% */
+#define  RTD2132_SSCG_CONFIG_1_0	0x0f	/* 1.0% */
+#define  RTD2132_SSCG_CONFIG_1_5	0x16	/* 1.5% */
+
+/* Configuration values from devicetree */
+#define RTD2132_SSCG_PERCENT_0_0	0x00	/* DISABLED */
+#define RTD2132_SSCG_PERCENT_0_5	0x05	/* 0.5% */
+#define RTD2132_SSCG_PERCENT_1_0	0x10	/* 1.0% */
+#define RTD2132_SSCG_PERCENT_1_5	0x15	/* 1.5% */
+
+static void rtd2132_firmware_stop(device_t dev)
+{
+	smbus_write_byte(dev, RTD2132_FIRMWARE, RTD2132_FIRMWARE_STOP);
+	mdelay(2);
+}
+
+static void rtd2132_firmware_start(device_t dev)
+{
+	smbus_write_byte(dev, RTD2132_FIRMWARE, RTD2132_FIRMWARE_START);
+}
+
+static void rtd2132_sscg_enable(device_t dev, u8 sscg_percent)
+{
+	/* SSCG_Config_0 */
+	smbus_write_byte(dev, RTD2132_COMMAND, RTD2132_COMMAND_SSCG_CONFIG_0);
+	smbus_write_byte(dev, RTD2132_DATA, RTD2132_SSCG_ENABLE);
+
+	/* SSCG_Config_1 */
+	smbus_write_byte(dev, RTD2132_COMMAND, RTD2132_COMMAND_SSCG_CONFIG_1);
+	smbus_write_byte(dev, RTD2132_DATA, sscg_percent);
+}
+
+static void rtd2132_sscg_disable(device_t dev)
+{
+	/* SSCG_Config_0 */
+	smbus_write_byte(dev, RTD2132_COMMAND, RTD2132_COMMAND_SSCG_CONFIG_0);
+	smbus_write_byte(dev, RTD2132_DATA, RTD2132_SSCG_DISABLE);
+
+	/* SSCG_Config_1 */
+	smbus_write_byte(dev, RTD2132_COMMAND, RTD2132_COMMAND_SSCG_CONFIG_1);
+	smbus_write_byte(dev, RTD2132_DATA, RTD2132_SSCG_CONFIG_DISABLED);
+}
+
+static void rtd2132_setup(device_t dev)
+{
+	struct drivers_i2c_rtd2132_config *config = dev->chip_info;
+
+	if (!config)
+		return;
+
+	/* Stop running firmware */
+	rtd2132_firmware_stop(dev);
+
+	/* Spread spectrum configuration */
+	switch (config->sscg_percent) {
+	case RTD2132_SSCG_PERCENT_0_0:
+		printk(BIOS_INFO, "RTD2132: Disable Spread Spectrum\n");
+		rtd2132_sscg_disable(dev);
+		break;
+	case RTD2132_SSCG_PERCENT_0_5:
+		printk(BIOS_INFO, "RTD2132: Enable 0.5%% Spread Spectrum\n");
+		rtd2132_sscg_enable(dev, RTD2132_SSCG_CONFIG_0_5);
+		break;
+	case RTD2132_SSCG_PERCENT_1_0:
+		printk(BIOS_INFO, "RTD2132: Enable 1.0%% Spread Spectrum\n");
+		rtd2132_sscg_enable(dev, RTD2132_SSCG_CONFIG_1_0);
+		break;
+	case RTD2132_SSCG_PERCENT_1_5:
+		printk(BIOS_INFO, "RTD2132: Enable 1.5%% Spread Spectrum\n");
+		rtd2132_sscg_enable(dev, RTD2132_SSCG_CONFIG_1_5);
+		break;
+	default:
+		printk(BIOS_ERR, "RTD2132: Invalid Spread Spectrum 0x%02x\n",
+		       config->sscg_percent);
+	}
+
+	/* Start firmware */
+	rtd2132_firmware_start(dev);
+}
+
+static void rtd2132_init(device_t dev)
+{
+	if (dev->enabled && dev->path.type == DEVICE_PATH_I2C &&
+	    ops_smbus_bus(get_pbus_smbus(dev))) {
+		rtd2132_setup(dev);
+	}
+}
+
+static void rtd2132_noop(device_t dummy)
+{
+}
+
+static struct device_operations rtd2132_operations = {
+	.read_resources		= rtd2132_noop,
+	.set_resources		= rtd2132_noop,
+	.enable_resources	= rtd2132_noop,
+	.init			= rtd2132_init,
+};
+
+static void enable_dev(struct device *dev)
+{
+	dev->ops = &rtd2132_operations;
+}
+
+struct chip_operations drivers_i2c_rtd2132_ops = {
+	CHIP_NAME("Realtek RTD2132 LVDS Bridge")
+	.enable_dev = enable_dev,
+};