feat(drivers): Add mcp23017 driver based on upstream mcp23s17 one.

* Upstream Zephyr has in progress driver, so doing this locally here,
  until we can move over to that driver.

app/drivers/CMakeLists.txt

@@ -1,6 +1,7 @@
 # Copyright (c) 2020 The ZMK Contributors
 # SPDX-License-Identifier: MIT
 
+add_subdirectory(gpio)
 add_subdirectory(kscan)
 add_subdirectory(sensor)
-add_subdirectory(display)
+add_subdirectory(display)

app/drivers/Kconfig

@@ -1,6 +1,7 @@
 # Copyright (c) 2020 The ZMK Contributors
 # SPDX-License-Identifier: MIT
 
+rsource "gpio/Kconfig"
 rsource "kscan/Kconfig"
 rsource "sensor/Kconfig"
-rsource "display/Kconfig"
+rsource "display/Kconfig"

app/drivers/gpio/CMakeLists.txt

@@ -0,0 +1,8 @@
+# Copyright (c) 2020 The ZMK Contributors
+# SPDX-License-Identifier: MIT
+
+zephyr_library_named(zmk__drivers__gpio)
+zephyr_library_include_directories(${CMAKE_SOURCE_DIR}/include)
+
+zephyr_library_sources_ifdef(CONFIG_GPIO_MCP23017 gpio_mcp23017.c)
+zephyr_library_sources_ifndef(CONFIG_GPIO_MCP23017 ${ZEPHYR_BASE}/misc/empty_file.c)

app/drivers/gpio/Kconfig

@@ -0,0 +1 @@
+rsource "Kconfig.mcp23017"

app/drivers/gpio/Kconfig.mcp23017

@@ -0,0 +1,21 @@
+# MCP23017 GPIO configuration options
+
+# Copyright (c) 2021 Pete Johanson
+# SPDX-License-Identifier: Apache-2.0
+
+menuconfig GPIO_MCP23017
+	bool "MCP23017 I2C-based GPIO chip"
+	depends on I2C
+	select HAS_DTS_GPIO
+	help
+	  Enable driver for MCP23017 I2C-based GPIO chip.
+
+if GPIO_MCP23017
+
+config GPIO_MCP23017_INIT_PRIORITY
+	int "Init priority"
+	default 75
+	help
+	  Device driver initialization priority.
+
+endif #GPIO_MCP23017

app/drivers/gpio/gpio_mcp23017.c

@@ -0,0 +1,332 @@
+/*
+ * Copyright (c) 2020 Geanix ApS
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#define DT_DRV_COMPAT microchip_mcp23017
+
+/**
+ * @file Driver for MCP23017 SPI-based GPIO driver.
+ */
+
+#include <errno.h>
+
+#include <kernel.h>
+#include <device.h>
+#include <init.h>
+#include <sys/byteorder.h>
+#include <drivers/gpio.h>
+#include <drivers/i2c.h>
+
+#include "gpio_mcp23017.h"
+
+#define LOG_LEVEL CONFIG_GPIO_LOG_LEVEL
+#include <logging/log.h>
+LOG_MODULE_REGISTER(gpio_mcp23017);
+
+/**
+ * @brief Read both port 0 and port 1 registers of certain register function.
+ *
+ * Given the register in reg, read the pair of port 0 and port 1.
+ *
+ * @param dev Device struct of the MCP23017.
+ * @param reg Register to read (the PORTA of the pair of registers).
+ * @param buf Buffer to read data into.
+ *
+ * @return 0 if successful, failed otherwise.
+ */
+static int read_port_regs(const struct device *dev, uint8_t reg, uint16_t *buf) {
+    const struct mcp23017_config *const config = dev->config;
+    struct mcp23017_drv_data *const drv_data = (struct mcp23017_drv_data *const)dev->data;
+    int ret;
+    uint16_t port_data;
+
+    uint8_t addr = config->slave;
+
+    ret = i2c_burst_read(drv_data->i2c, addr, reg, (uint8_t *)&port_data, sizeof(port_data));
+    if (ret) {
+        LOG_DBG("i2c_write_read FAIL %d\n", ret);
+        return ret;
+    }
+
+    *buf = sys_le16_to_cpu(port_data);
+
+    LOG_DBG("MCP23017: Read: REG[0x%X] = 0x%X, REG[0x%X] = 0x%X", reg, (*buf & 0xFF), (reg + 1),
+            (*buf >> 8));
+
+    return 0;
+}
+
+/**
+ * @brief Write both port 0 and port 1 registers of certain register function.
+ *
+ * Given the register in reg, write the pair of port 0 and port 1.
+ *
+ * @param dev Device struct of the MCP23017.
+ * @param reg Register to write into (the PORTA of the pair of registers).
+ * @param buf Buffer to write data from.
+ *
+ * @return 0 if successful, failed otherwise.
+ */
+static int write_port_regs(const struct device *dev, uint8_t reg, uint16_t value) {
+    const struct mcp23017_config *const config = dev->config;
+    struct mcp23017_drv_data *const drv_data = (struct mcp23017_drv_data *const)dev->data;
+    int ret;
+    uint16_t port_data;
+
+    LOG_DBG("MCP23017: Write: REG[0x%X] = 0x%X, REG[0x%X] = 0x%X", reg, (value & 0xFF), (reg + 1),
+            (value >> 8));
+
+    port_data = sys_cpu_to_le16(value);
+
+    ret = i2c_burst_write(drv_data->i2c, config->slave, reg, (uint8_t *)&port_data,
+                          sizeof(port_data));
+    if (ret) {
+        LOG_DBG("i2c_write FAIL %d\n", ret);
+        return ret;
+    }
+
+    return 0;
+}
+
+/**
+ * @brief Setup the pin direction (input or output)
+ *
+ * @param dev Device struct of the MCP23017
+ * @param pin The pin number
+ * @param flags Flags of pin or port
+ *
+ * @return 0 if successful, failed otherwise
+ */
+static int setup_pin_dir(const struct device *dev, uint32_t pin, int flags) {
+    struct mcp23017_drv_data *const drv_data = (struct mcp23017_drv_data *const)dev->data;
+    uint16_t *dir = &drv_data->reg_cache.iodir;
+    uint16_t *output = &drv_data->reg_cache.gpio;
+    int ret;
+
+    if ((flags & GPIO_OUTPUT) != 0U) {
+        if ((flags & GPIO_OUTPUT_INIT_HIGH) != 0U) {
+            *output |= BIT(pin);
+        } else if ((flags & GPIO_OUTPUT_INIT_LOW) != 0U) {
+            *output &= ~BIT(pin);
+        }
+        *dir &= ~BIT(pin);
+    } else {
+        *dir |= BIT(pin);
+    }
+
+    ret = write_port_regs(dev, REG_GPIO_PORTA, *output);
+    if (ret != 0) {
+        return ret;
+    }
+
+    ret = write_port_regs(dev, REG_IODIR_PORTA, *dir);
+
+    return ret;
+}
+
+/**
+ * @brief Setup the pin pull up/pull down status
+ *
+ * @param dev Device struct of the MCP23017
+ * @param pin The pin number
+ * @param flags Flags of pin or port
+ *
+ * @return 0 if successful, failed otherwise
+ */
+static int setup_pin_pullupdown(const struct device *dev, uint32_t pin, int flags) {
+    struct mcp23017_drv_data *const drv_data = (struct mcp23017_drv_data *const)dev->data;
+    uint16_t port;
+    int ret;
+
+    /* Setup pin pull up or pull down */
+    port = drv_data->reg_cache.gppu;
+
+    /* pull down == 0, pull up == 1 */
+    if ((flags & GPIO_PULL_DOWN) != 0U) {
+        return -ENOTSUP;
+    }
+
+    WRITE_BIT(port, pin, (flags & GPIO_PULL_UP) != 0U);
+
+    ret = write_port_regs(dev, REG_GPPU_PORTA, port);
+    if (ret == 0) {
+        drv_data->reg_cache.gppu = port;
+    }
+
+    return ret;
+}
+
+static int mcp23017_config(const struct device *dev, gpio_pin_t pin, gpio_flags_t flags) {
+    struct mcp23017_drv_data *const drv_data = (struct mcp23017_drv_data *const)dev->data;
+    int ret;
+
+    /* Can't do SPI bus operations from an ISR */
+    if (k_is_in_isr()) {
+        return -EWOULDBLOCK;
+    }
+
+    k_sem_take(&drv_data->lock, K_FOREVER);
+
+    if ((flags & GPIO_OPEN_DRAIN) != 0U) {
+        ret = -ENOTSUP;
+        goto done;
+    };
+
+    ret = setup_pin_dir(dev, pin, flags);
+    if (ret) {
+        LOG_ERR("MCP23017: error setting pin direction (%d)", ret);
+        goto done;
+    }
+
+    ret = setup_pin_pullupdown(dev, pin, flags);
+    if (ret) {
+        LOG_ERR("MCP23017: error setting pin pull up/down (%d)", ret);
+        goto done;
+    }
+
+done:
+    k_sem_give(&drv_data->lock);
+    return ret;
+}
+
+static int mcp23017_port_get_raw(const struct device *dev, uint32_t *value) {
+    struct mcp23017_drv_data *const drv_data = (struct mcp23017_drv_data *const)dev->data;
+    uint16_t buf;
+    int ret;
+
+    /* Can't do SPI bus operations from an ISR */
+    if (k_is_in_isr()) {
+        return -EWOULDBLOCK;
+    }
+
+    k_sem_take(&drv_data->lock, K_FOREVER);
+
+    ret = read_port_regs(dev, REG_GPIO_PORTA, &buf);
+    if (ret != 0) {
+        goto done;
+    }
+
+    *value = buf;
+
+done:
+    k_sem_give(&drv_data->lock);
+    return ret;
+}
+
+static int mcp23017_port_set_masked_raw(const struct device *dev, uint32_t mask, uint32_t value) {
+    struct mcp23017_drv_data *const drv_data = (struct mcp23017_drv_data *const)dev->data;
+    uint16_t buf;
+    int ret;
+
+    /* Can't do SPI bus operations from an ISR */
+    if (k_is_in_isr()) {
+        return -EWOULDBLOCK;
+    }
+
+    k_sem_take(&drv_data->lock, K_FOREVER);
+
+    buf = drv_data->reg_cache.gpio;
+    buf = (buf & ~mask) | (mask & value);
+
+    ret = write_port_regs(dev, REG_GPIO_PORTA, buf);
+    if (ret == 0) {
+        drv_data->reg_cache.gpio = buf;
+    }
+
+    k_sem_give(&drv_data->lock);
+
+    return ret;
+}
+
+static int mcp23017_port_set_bits_raw(const struct device *dev, uint32_t mask) {
+    return mcp23017_port_set_masked_raw(dev, mask, mask);
+}
+
+static int mcp23017_port_clear_bits_raw(const struct device *dev, uint32_t mask) {
+    return mcp23017_port_set_masked_raw(dev, mask, 0);
+}
+
+static int mcp23017_port_toggle_bits(const struct device *dev, uint32_t mask) {
+    struct mcp23017_drv_data *const drv_data = (struct mcp23017_drv_data *const)dev->data;
+    uint16_t buf;
+    int ret;
+
+    /* Can't do SPI bus operations from an ISR */
+    if (k_is_in_isr()) {
+        return -EWOULDBLOCK;
+    }
+
+    k_sem_take(&drv_data->lock, K_FOREVER);
+
+    buf = drv_data->reg_cache.gpio;
+    buf ^= mask;
+
+    ret = write_port_regs(dev, REG_GPIO_PORTA, buf);
+    if (ret == 0) {
+        drv_data->reg_cache.gpio = buf;
+    }
+
+    k_sem_give(&drv_data->lock);
+
+    return ret;
+}
+
+static int mcp23017_pin_interrupt_configure(const struct device *dev, gpio_pin_t pin,
+                                            enum gpio_int_mode mode, enum gpio_int_trig trig) {
+    return -ENOTSUP;
+}
+
+static const struct gpio_driver_api api_table = {
+    .pin_configure = mcp23017_config,
+    .port_get_raw = mcp23017_port_get_raw,
+    .port_set_masked_raw = mcp23017_port_set_masked_raw,
+    .port_set_bits_raw = mcp23017_port_set_bits_raw,
+    .port_clear_bits_raw = mcp23017_port_clear_bits_raw,
+    .port_toggle_bits = mcp23017_port_toggle_bits,
+    .pin_interrupt_configure = mcp23017_pin_interrupt_configure,
+};
+
+/**
+ * @brief Initialization function of MCP23017
+ *
+ * @param dev Device struct
+ * @return 0 if successful, failed otherwise.
+ */
+static int mcp23017_init(const struct device *dev) {
+    const struct mcp23017_config *const config = dev->config;
+    struct mcp23017_drv_data *const drv_data = (struct mcp23017_drv_data *const)dev->data;
+
+    drv_data->i2c = device_get_binding((char *)config->i2c_dev_name);
+    if (!drv_data->i2c) {
+        LOG_DBG("Unable to get i2c device");
+        return -ENODEV;
+    }
+
+    k_sem_init(&drv_data->lock, 1, 1);
+
+    return 0;
+}
+
+#define MCP23017_INIT(inst)                                                                        \
+    static struct mcp23017_config mcp23017_##inst##_config = {                                     \
+        .i2c_dev_name = DT_INST_BUS_LABEL(inst),                                                   \
+        .slave = DT_INST_REG_ADDR(inst),                                                           \
+                                                                                                   \
+    };                                                                                             \
+                                                                                                   \
+    static struct mcp23017_drv_data mcp23017_##inst##_drvdata = {                                  \
+        /* Default for registers according to datasheet */                                         \
+        .reg_cache.iodir = 0xFFFF, .reg_cache.ipol = 0x0,   .reg_cache.gpinten = 0x0,              \
+        .reg_cache.defval = 0x0,   .reg_cache.intcon = 0x0, .reg_cache.iocon = 0x0,                \
+        .reg_cache.gppu = 0x0,     .reg_cache.intf = 0x0,   .reg_cache.intcap = 0x0,               \
+        .reg_cache.gpio = 0x0,     .reg_cache.olat = 0x0,                                          \
+    };                                                                                             \
+                                                                                                   \
+    /* This has to init after SPI master */                                                        \
+    DEVICE_DT_INST_DEFINE(inst, mcp23017_init, device_pm_control_nop, &mcp23017_##inst##_drvdata,  \
+                          &mcp23017_##inst##_config, POST_KERNEL,                                  \
+                          CONFIG_GPIO_MCP23017_INIT_PRIORITY, &api_table);
+
+DT_INST_FOREACH_STATUS_OKAY(MCP23017_INIT)