retimer: Add emulator and unit tests for ANX7452 retimer driver

BUG=b:267589042
BRANCH=none
TEST=./twister -s drivers/drivers.anx7452 -c --coverage

Change-Id: I7b4dcef7e667cd69ecb39f6dda7a6c8570177f40
Signed-off-by: Madhurima Paruchuri <mparuchuri@google.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/4303379
Reviewed-by: Fabio Baltieri <fabiobaltieri@google.com>

3 files changed, 274 insertions, 0 deletions

diff --git a/zephyr/emul/CMakeLists.txt b/zephyr/emul/CMakeLists.txt
index 523e1e98b0..58eef44627 100644
--- a/zephyr/emul/CMakeLists.txt
+++ b/zephyr/emul/CMakeLists.txt
@@ -7,6 +7,7 @@ add_subdirectory("tcpc")
 
 cros_ec_library_include_directories(include)
 
+zephyr_library_sources_ifdef(CONFIG_EMUL_ANX7452	emul_anx7452.c)
 zephyr_library_sources_ifdef(CONFIG_EMUL_BB_RETIMER	emul_bb_retimer.c)
 zephyr_library_sources_ifdef(CONFIG_EMUL_BC12_DETECT_PI3USB9201	emul_pi3usb9201.c)
 zephyr_library_sources_ifdef(CONFIG_EMUL_BMA255		emul_bma255.c)
diff --git a/zephyr/emul/Kconfig b/zephyr/emul/Kconfig
index b160e430b2..ecdbfb426c 100644
--- a/zephyr/emul/Kconfig
+++ b/zephyr/emul/Kconfig
@@ -190,6 +190,17 @@ config EMUL_PCT2075
 	  Enable the PCT2075 temperature sensor emulator. It uses emulated I2C bus.
 	  Emulator API is available in zephyr/include/emul/emul_pct2075.h.
 
+config EMUL_ANX7452
+	bool "ANX7452 retimer emulator"
+	default y
+	depends on ZTEST && DT_HAS_ANALOGIX_ANX7452_ENABLED
+	select EMUL_COMMON_I2C
+	help
+	  Enable the ANX7452(Analogix) retimer emulator. This driver use
+	  emulated I2C bus. It is used to test anx7452 driver. It supports
+	  reads and writes to all emulator registers. Emulators API is
+	  available in zephyr/include/emul/emul_anx7452.h
+
 config EMUL_PS8743
 	bool "PS8743 emulator"
 	default y
diff --git a/zephyr/emul/emul_anx7452.c b/zephyr/emul/emul_anx7452.c
new file mode 100644
index 0000000000..f9854d4081
--- /dev/null
+++ b/zephyr/emul/emul_anx7452.c
@@ -0,0 +1,262 @@
+/* Copyright 2023 The ChromiumOS Authors
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "driver/retimer/anx7452.h"
+#include "emul/emul_anx7452.h"
+#include "emul/emul_common_i2c.h"
+#include "emul/emul_stub_device.h"
+
+#include <zephyr/device.h>
+#include <zephyr/drivers/emul.h>
+#include <zephyr/drivers/i2c.h>
+#include <zephyr/drivers/i2c_emul.h>
+#include <zephyr/logging/log.h>
+
+#define DT_DRV_COMPAT analogix_anx7452
+
+#define LOG_LEVEL CONFIG_I2C_LOG_LEVEL
+LOG_MODULE_REGISTER(emul_anx7452);
+
+/** Run-time data used by the emulator */
+struct anx7452_emul_data {
+	/** Common I2C data */
+	struct i2c_common_emul_data top_data;
+	struct i2c_common_emul_data ctltop_data;
+
+	/** Configuration information */
+	const struct anx7452_emul_cfg *cfg;
+
+	/** Current state of all emulated ANX7452 retimer registers */
+	uint8_t top_reg;
+
+	uint8_t ctltop_cfg0_reg;
+
+	uint8_t ctltop_cfg1_reg;
+
+	uint8_t ctltop_cfg2_reg;
+};
+
+/** Constant configuration of the emulator */
+struct anx7452_emul_cfg {
+	const struct i2c_common_emul_cfg top_cfg;
+	const struct i2c_common_emul_cfg ctltop_cfg;
+};
+
+/* Workhorse for mapping i2c reg to internal emulator data access */
+static uint8_t *anx7452_emul_get_reg_ptr(struct anx7452_emul_data *data,
+					 int reg)
+{
+	switch (reg) {
+	case ANX7452_TOP_STATUS_REG:
+		return &(data->top_reg);
+	case ANX7452_CTLTOP_CFG0_REG:
+		return &(data->ctltop_cfg0_reg);
+	case ANX7452_CTLTOP_CFG1_REG:
+		return &(data->ctltop_cfg1_reg);
+	case ANX7452_CTLTOP_CFG2_REG:
+		return &(data->ctltop_cfg2_reg);
+	default:
+		__ASSERT(false, "Unimplemented Register Access Error on 0x%x",
+			 reg);
+		/* Statement never reached, required for compiler warnings */
+		return NULL;
+	}
+}
+
+/** Check description in emul_anx7452.h */
+void anx7452_emul_set_reg(const struct emul *emul, int reg, uint8_t val)
+{
+	struct anx7452_emul_data *data = emul->data;
+
+	uint8_t *reg_to_write = anx7452_emul_get_reg_ptr(data, reg);
+	*reg_to_write = val;
+}
+
+/** Check description in emul_anx7452.h */
+uint8_t anx7452_emul_get_reg(const struct emul *emul, int reg)
+{
+	struct anx7452_emul_data *data = emul->data;
+	uint8_t *reg_to_read = anx7452_emul_get_reg_ptr(data, reg);
+
+	return *reg_to_read;
+}
+
+/** Check description in emul_anx7452.h */
+void anx7452_emul_reset(const struct emul *emul)
+{
+	struct anx7452_emul_data *data;
+
+	data = emul->data;
+
+	data->top_reg = 0xFF;
+
+	data->ctltop_cfg0_reg = 0x00;
+
+	data->ctltop_cfg1_reg = 0x00;
+
+	data->ctltop_cfg2_reg = 0x00;
+}
+
+static int anx7452_emul_write_byte(const struct emul *emul, int reg,
+				   uint8_t val, int bytes)
+{
+	struct anx7452_emul_data *data = emul->data;
+
+	uint8_t *reg_to_write = anx7452_emul_get_reg_ptr(data, reg);
+	*reg_to_write = val;
+
+	return 0;
+}
+
+static int anx7452_emul_read_byte(const struct emul *emul, int reg,
+				  uint8_t *val, int bytes)
+{
+	struct anx7452_emul_data *data = emul->data;
+	uint8_t *reg_to_read = anx7452_emul_get_reg_ptr(data, reg);
+
+	*val = *reg_to_read;
+
+	return 0;
+}
+
+/**
+ * Emulate an I2C transfer for ANX7452
+ *
+ * This handles simple reads and writes
+ *
+ * @param emul I2C emulation information
+ * @param msgs List of messages to process
+ * @param num_msgs Number of messages to process
+ * @param addr Address of the I2C target device
+ *
+ * @retval 0 If successful
+ * @retval -EIO General input / output error
+ */
+static int anx7452_emul_transfer(const struct emul *emul, struct i2c_msg *msgs,
+				 int num_msgs, int addr)
+{
+	const struct anx7452_emul_cfg *cfg;
+	struct anx7452_emul_data *data;
+	struct i2c_common_emul_data *common_data;
+
+	data = emul->data;
+	cfg = emul->cfg;
+
+	if (addr == cfg->top_cfg.addr) {
+		const struct i2c_common_emul_cfg *common_cfg = &cfg->top_cfg;
+
+		common_data = &data->top_data;
+		return i2c_common_emul_transfer_workhorse(
+			emul, common_data, common_cfg, msgs, num_msgs, addr);
+	} else if (addr == cfg->ctltop_cfg.addr) {
+		const struct i2c_common_emul_cfg *common_cfg = &cfg->ctltop_cfg;
+
+		common_data = &data->ctltop_data;
+		return i2c_common_emul_transfer_workhorse(
+			emul, common_data, common_cfg, msgs, num_msgs, addr);
+	}
+
+	LOG_ERR("Cannot map address %02x", addr);
+	return -EIO;
+}
+
+/* Device instantiation */
+
+static struct i2c_emul_api anx7452_emul_api = {
+	.transfer = anx7452_emul_transfer,
+};
+
+/* Device instantiation */
+
+/**
+ * @brief Set up a new ANX7452 retimer emulator
+ *
+ * This should be called for each ANX7452 retimer device that needs to be
+ * emulated. It registers it with the I2C emulation controller.
+ *
+ * @param emul Emulation information
+ * @param parent Device to emulate
+ *
+ * @return 0 indicating success (always)
+ */
+static int anx7452_emul_init(const struct emul *emul,
+			     const struct device *parent)
+{
+	const struct anx7452_emul_cfg *cfg;
+	struct anx7452_emul_data *data;
+	int ret = 0;
+
+	data = emul->data;
+	cfg = emul->cfg;
+
+	data->top_data.emul.api = &anx7452_emul_api;
+	data->top_data.emul.addr = cfg->top_cfg.addr;
+	data->top_data.emul.target = emul;
+	data->top_data.i2c = parent;
+	data->top_data.cfg = &cfg->top_cfg;
+	i2c_common_emul_init(&data->top_data);
+
+	data->ctltop_data.emul.api = &anx7452_emul_api;
+	data->ctltop_data.emul.addr = cfg->ctltop_cfg.addr;
+	data->ctltop_data.emul.target = emul;
+	data->ctltop_data.i2c = parent;
+	data->ctltop_data.cfg = &cfg->ctltop_cfg;
+	i2c_common_emul_init(&data->ctltop_data);
+
+	ret |= i2c_emul_register(parent, &data->top_data.emul);
+	ret |= i2c_emul_register(parent, &data->ctltop_data.emul);
+
+	anx7452_emul_reset(emul);
+
+	return ret;
+}
+
+#define ANX7452_EMUL(n)                                                   \
+	static struct anx7452_emul_data anx7452_emul_data_##n = {	  \
+		.top_data = {						  \
+			.write_byte = anx7452_emul_write_byte,		  \
+			.read_byte = anx7452_emul_read_byte,		  \
+		},                                                        \
+		.ctltop_data = {					  \
+			.write_byte = anx7452_emul_write_byte,		  \
+			.read_byte = anx7452_emul_read_byte,		  \
+		},							  \
+	};     \
+	static const struct anx7452_emul_cfg anx7452_emul_cfg_##n = {	\
+		.top_cfg = {						\
+			.dev_label = DT_NODE_FULL_NAME(DT_DRV_INST(n)), \
+			.data = &anx7452_emul_data_##n.top_data,	\
+			.addr = DT_INST_REG_ADDR(n),		\
+		},							\
+		.ctltop_cfg = {						\
+			.dev_label = DT_NODE_FULL_NAME(DT_DRV_INST(n)), \
+			.data = &anx7452_emul_data_##n.ctltop_data,	\
+			.addr = ANX7452_I2C_ADDR_CTLTOP_FLAGS,		\
+		},		                                        \
+	};   \
+	EMUL_DT_INST_DEFINE(n, anx7452_emul_init, &anx7452_emul_data_##n, \
+			    &anx7452_emul_cfg_##n, &anx7452_emul_api, NULL)
+
+DT_INST_FOREACH_STATUS_OKAY(ANX7452_EMUL);
+
+DT_INST_FOREACH_STATUS_OKAY(EMUL_STUB_DEVICE);
+
+struct i2c_common_emul_data *
+emul_anx7452_get_i2c_common_data(const struct emul *emul,
+				 enum anx7452_emul_port port)
+{
+	struct anx7452_emul_data *data;
+
+	data = emul->data;
+
+	switch (port) {
+	case TOP_EMUL_PORT:
+		return &data->top_data;
+	case CTLTOP_EMUL_PORT:
+		return &data->ctltop_data;
+	default:
+		return NULL;
+	}
+}