drivers/i2c: Add chip driver for I/O expander PCA9538

The chip PCA9538 is a 8 bit I/O expander connected to the systems I2C
bus. Add a chip driver to support this chip.

Beside the pure chip driver two interface functions are provided to read
the state of the pins and write output values to the pins.
As the slave address of this chip is hardware configurable the function
pca9538_get_dev() is used to get the right slave address. This function
needs to be implemented in mainboard code if one needs to use the
interface functions to read and write I/O state.

Change-Id: Ic856123b4f4c8b721928ee3a2a4bb37833ea4b20
Signed-off-by: Werner Zeh <werner.zeh@siemens.com>
Reviewed-on: https://review.coreboot.org/23748
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/drivers/i2c/pca9538/Kconfig

@@ -0,0 +1,5 @@
+config DRIVERS_I2C_PCA9538
+	bool
+	default n
+	help
+	  Enable support for I2C I/O expander PCA9538.

src/drivers/i2c/pca9538/Makefile.inc

@@ -0,0 +1,5 @@
+ramstage-$(CONFIG_DRIVERS_I2C_PCA9538) += pca9538.c
+
+ifeq ($(CONFIG_DRIVERS_I2C_PCA9538),y)
+CFLAGS_common += -Isrc/drivers/i2c/pca9538
+endif

src/drivers/i2c/pca9538/chip.h

@@ -0,0 +1,21 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2018 Siemens AG
+ *
+ * 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.
+ */
+
+
+struct drivers_i2c_pca9538_config {
+	unsigned char in_out;	/* Use bit as input(1) or output (0). */
+	unsigned char invert;	/* If a bit is 1, the input will be inverted. */
+	unsigned char out_val;	/* Initial output value to drive. */
+};

src/drivers/i2c/pca9538/pca9538.c

@@ -0,0 +1,70 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2018 Siemens AG
+ *
+ * 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.
+ */
+
+#include <device/i2c_bus.h>
+#include <device/device.h>
+#include <console/console.h>
+#include "pca9538.h"
+#include "chip.h"
+
+/* This function can be used from outside the chip driver to read input. */
+uint8_t pca9538_read_input(void)
+{
+	struct device *dev = pca9538_get_dev();
+
+	if (!dev)
+		return 0;
+	else
+		return (uint8_t)(i2c_dev_readb_at(dev, INPUT_REG));
+}
+
+/* This function can be used from outside the chip driver to set output. */
+void pca9538_set_output(uint8_t val)
+{
+	struct device *dev = pca9538_get_dev();
+
+	if (dev)
+		i2c_dev_writeb_at(dev, OUTPUT_REG, val);
+}
+
+static void pca9538_init(struct device *dev)
+{
+	struct drivers_i2c_pca9538_config *config = dev->chip_info;
+
+	if (!config)
+		return;
+	/* Set up registers as requested in devicetree. */
+	i2c_dev_writeb_at(dev, INPUT_INVERT_REG, config->invert);
+	i2c_dev_writeb_at(dev, OUTPUT_REG, config->out_val);
+	i2c_dev_writeb_at(dev, IO_CONFIG_REG, config->in_out);
+}
+
+static struct device_operations pca9538_ops = {
+	.read_resources		= DEVICE_NOOP,
+	.set_resources		= DEVICE_NOOP,
+	.enable_resources	= DEVICE_NOOP,
+	.init			= pca9538_init,
+	.final			= DEVICE_NOOP
+};
+
+static void pca9538_enable(struct device *dev)
+{
+	dev->ops = &pca9538_ops;
+}
+
+struct chip_operations drivers_i2c_pca9538_ops = {
+	CHIP_NAME("PCA9538")
+	.enable_dev = pca9538_enable
+};

src/drivers/i2c/pca9538/pca9538.h

@@ -0,0 +1,38 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2018 Siemens AG
+ *
+ * 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.
+ */
+
+#ifndef _I2C_PCA9538_H_
+#define _I2C_PCA9538_H_
+
+#include <types.h>
+#include <device/device.h>
+
+/* Register layout */
+#define INPUT_REG		0x00
+#define OUTPUT_REG		0x01
+#define INPUT_INVERT_REG	0x02
+#define IO_CONFIG_REG		0x03
+
+/* Provide some functions to read input and write output values. */
+uint8_t pca9538_read_input(void);
+void pca9538_set_output(uint8_t val);
+/*
+ * Provide a way to get the right device structure for the I/O expander.
+ * The user of this driver has to provide this function if read/write of I/O
+ * values on the I/O expander is needed.
+ */
+struct device *pca9538_get_dev(void);
+
+#endif /* _I2C_PCA9538_H_ */