// SPDX-License-Identifier: GPL-2.0
/*
 * KUnit test for the generic kernel FIFO implementation.
 *
 * Copyright (C) 2024 Diego Vieira <diego.daniel.professional@gmail.com>
 */
#include <kunit/test.h>

#include <linux/kfifo.h>

#define KFIFO_SIZE 32
#define N_ELEMENTS 5

static void kfifo_test_reset_should_clear_the_fifo(struct kunit *test)
{
        DEFINE_KFIFO(my_fifo, u8, KFIFO_SIZE);

        kfifo_put(&my_fifo, 1);
        kfifo_put(&my_fifo, 2);
        kfifo_put(&my_fifo, 3);
        KUNIT_EXPECT_EQ(test, kfifo_len(&my_fifo), 3);

        kfifo_reset(&my_fifo);

        KUNIT_EXPECT_EQ(test, kfifo_len(&my_fifo), 0);
        KUNIT_EXPECT_TRUE(test, kfifo_is_empty(&my_fifo));
}

static void kfifo_test_define_should_define_an_empty_fifo(struct kunit *test)
{
        DEFINE_KFIFO(my_fifo, u8, KFIFO_SIZE);

        KUNIT_EXPECT_TRUE(test, kfifo_initialized(&my_fifo));
        KUNIT_EXPECT_TRUE(test, kfifo_is_empty(&my_fifo));
        KUNIT_EXPECT_EQ(test, kfifo_len(&my_fifo), 0);
}

static void kfifo_test_len_should_ret_n_of_stored_elements(struct kunit *test)
{
        u8 buffer1[N_ELEMENTS];

        for (int i = 0; i < N_ELEMENTS; i++)
                buffer1[i] = i + 1;

        DEFINE_KFIFO(my_fifo, u8, KFIFO_SIZE);

        KUNIT_EXPECT_EQ(test, kfifo_len(&my_fifo), 0);

        kfifo_in(&my_fifo, buffer1, N_ELEMENTS);
        KUNIT_EXPECT_EQ(test, kfifo_len(&my_fifo), N_ELEMENTS);

        kfifo_in(&my_fifo, buffer1, N_ELEMENTS);
        KUNIT_EXPECT_EQ(test, kfifo_len(&my_fifo), N_ELEMENTS * 2);

        kfifo_reset(&my_fifo);
        KUNIT_EXPECT_EQ(test, kfifo_len(&my_fifo), 0);
}

static void kfifo_test_put_should_insert_and_get_should_pop(struct kunit *test)
{
        u8 out_data = 0;
        int processed_elements;
        u8 elements[] = { 3, 5, 11 };

        DEFINE_KFIFO(my_fifo, u8, KFIFO_SIZE);

        // If the fifo is empty, get returns 0
        processed_elements = kfifo_get(&my_fifo, &out_data);
        KUNIT_EXPECT_EQ(test, processed_elements, 0);
        KUNIT_EXPECT_EQ(test, out_data, 0);

        for (int i = 0; i < 3; i++)
                kfifo_put(&my_fifo, elements[i]);

        for (int i = 0; i < 3; i++) {
                processed_elements = kfifo_get(&my_fifo, &out_data);
                KUNIT_EXPECT_EQ(test, processed_elements, 1);
                KUNIT_EXPECT_EQ(test, out_data, elements[i]);
        }
}

static void kfifo_test_in_should_insert_multiple_elements(struct kunit *test)
{
        u8 in_buffer[] = { 11, 25, 65 };
        u8 out_data;
        int processed_elements;

        DEFINE_KFIFO(my_fifo, u8, KFIFO_SIZE);

        kfifo_in(&my_fifo, in_buffer, 3);

        for (int i = 0; i < 3; i++) {
                processed_elements = kfifo_get(&my_fifo, &out_data);
                KUNIT_EXPECT_EQ(test, processed_elements, 1);
                KUNIT_EXPECT_EQ(test, out_data, in_buffer[i]);
        }
}

static void kfifo_test_out_should_pop_multiple_elements(struct kunit *test)
{
        u8 in_buffer[] = { 11, 25, 65 };
        u8 out_buffer[3];
        int copied_elements;

        DEFINE_KFIFO(my_fifo, u8, KFIFO_SIZE);

        for (int i = 0; i < 3; i++)
                kfifo_put(&my_fifo, in_buffer[i]);

        copied_elements = kfifo_out(&my_fifo, out_buffer, 3);
        KUNIT_EXPECT_EQ(test, copied_elements, 3);

        for (int i = 0; i < 3; i++)
                KUNIT_EXPECT_EQ(test, out_buffer[i], in_buffer[i]);
        KUNIT_EXPECT_TRUE(test, kfifo_is_empty(&my_fifo));
}

static void kfifo_test_dec_init_should_define_an_empty_fifo(struct kunit *test)
{
        DECLARE_KFIFO(my_fifo, u8, KFIFO_SIZE);

        INIT_KFIFO(my_fifo);

        // my_fifo is a struct with an inplace buffer
        KUNIT_EXPECT_FALSE(test, __is_kfifo_ptr(&my_fifo));

        KUNIT_EXPECT_TRUE(test, kfifo_initialized(&my_fifo));
}

static void kfifo_test_define_should_equal_declare_init(struct kunit *test)
{
        // declare a variable my_fifo of type struct kfifo of u8
        DECLARE_KFIFO(my_fifo1, u8, KFIFO_SIZE);
        // initialize the my_fifo variable
        INIT_KFIFO(my_fifo1);

        // DEFINE_KFIFO declares the variable with the initial value
        // essentially the same as calling DECLARE_KFIFO and INIT_KFIFO
        DEFINE_KFIFO(my_fifo2, u8, KFIFO_SIZE);

        // my_fifo1 and my_fifo2 have the same size
        KUNIT_EXPECT_EQ(test, sizeof(my_fifo1), sizeof(my_fifo2));
        KUNIT_EXPECT_EQ(test, kfifo_initialized(&my_fifo1),
                        kfifo_initialized(&my_fifo2));
        KUNIT_EXPECT_EQ(test, kfifo_is_empty(&my_fifo1),
                        kfifo_is_empty(&my_fifo2));
}

static void kfifo_test_alloc_should_initiliaze_a_ptr_fifo(struct kunit *test)
{
        int ret;
        DECLARE_KFIFO_PTR(my_fifo, u8);

        INIT_KFIFO(my_fifo);

        // kfifo_initialized returns false signaling the buffer pointer is NULL
        KUNIT_EXPECT_FALSE(test, kfifo_initialized(&my_fifo));

        // kfifo_alloc allocates the buffer
        ret = kfifo_alloc(&my_fifo, KFIFO_SIZE, GFP_KERNEL);
        KUNIT_EXPECT_EQ_MSG(test, ret, 0, "Memory allocation should succeed");
        KUNIT_EXPECT_TRUE(test, kfifo_initialized(&my_fifo));

        // kfifo_free frees the buffer
        kfifo_free(&my_fifo);
}

static void kfifo_test_peek_should_not_remove_elements(struct kunit *test)
{
        u8 out_data;
        int processed_elements;

        DEFINE_KFIFO(my_fifo, u8, KFIFO_SIZE);

        // If the fifo is empty, peek returns 0
        processed_elements = kfifo_peek(&my_fifo, &out_data);
        KUNIT_EXPECT_EQ(test, processed_elements, 0);

        kfifo_put(&my_fifo, 3);
        kfifo_put(&my_fifo, 5);
        kfifo_put(&my_fifo, 11);

        KUNIT_EXPECT_EQ(test, kfifo_len(&my_fifo), 3);

        processed_elements = kfifo_peek(&my_fifo, &out_data);
        KUNIT_EXPECT_EQ(test, processed_elements, 1);
        KUNIT_EXPECT_EQ(test, out_data, 3);

        KUNIT_EXPECT_EQ(test, kfifo_len(&my_fifo), 3);

        // Using peek doesn't remove the element
        // so the read element and the fifo length
        // remains the same
        processed_elements = kfifo_peek(&my_fifo, &out_data);
        KUNIT_EXPECT_EQ(test, processed_elements, 1);
        KUNIT_EXPECT_EQ(test, out_data, 3);

        KUNIT_EXPECT_EQ(test, kfifo_len(&my_fifo), 3);
}

static struct kunit_case kfifo_test_cases[] = {
        KUNIT_CASE(kfifo_test_reset_should_clear_the_fifo),
        KUNIT_CASE(kfifo_test_define_should_define_an_empty_fifo),
        KUNIT_CASE(kfifo_test_len_should_ret_n_of_stored_elements),
        KUNIT_CASE(kfifo_test_put_should_insert_and_get_should_pop),
        KUNIT_CASE(kfifo_test_in_should_insert_multiple_elements),
        KUNIT_CASE(kfifo_test_out_should_pop_multiple_elements),
        KUNIT_CASE(kfifo_test_dec_init_should_define_an_empty_fifo),
        KUNIT_CASE(kfifo_test_define_should_equal_declare_init),
        KUNIT_CASE(kfifo_test_alloc_should_initiliaze_a_ptr_fifo),
        KUNIT_CASE(kfifo_test_peek_should_not_remove_elements),
        {},
};

static struct kunit_suite kfifo_test_module = {
        .name = "kfifo",
        .test_cases = kfifo_test_cases,
};

kunit_test_suites(&kfifo_test_module);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Diego Vieira <diego.daniel.professional@gmail.com>");
MODULE_DESCRIPTION("KUnit test for the kernel FIFO");