[v3,5/5] tests/qtest: Add tests for the STM32L4x5 USART

diff --git a/tests/qtest/meson.build b/tests/qtest/meson.build
index 36c5c13a7b..b128fa5a4b 100644
--- a/tests/qtest/meson.build
+++ b/tests/qtest/meson.build
@@ -7,6 +7,7 @@  slow_qtests = {
   'npcm7xx_pwm-test': 300,
   'npcm7xx_watchdog_timer-test': 120,
   'qom-test' : 900,
+  'stm32l4x5_usart-test' : 600,
   'test-hmp' : 240,
   'pxe-test': 610,
   'prom-env-test': 360,
@@ -205,7 +206,8 @@  qtests_stm32l4x5 = \
   ['stm32l4x5_exti-test',
    'stm32l4x5_syscfg-test',
    'stm32l4x5_rcc-test',
-   'stm32l4x5_gpio-test']
+   'stm32l4x5_gpio-test',
+   'stm32l4x5_usart-test']
 
 qtests_arm = \
   (config_all_devices.has_key('CONFIG_MPS2') ? ['sse-timer-test'] : []) + \
diff --git a/tests/qtest/stm32l4x5_usart-test.c b/tests/qtest/stm32l4x5_usart-test.c
new file mode 100644
index 0000000000..ca6aa33ff6
--- /dev/null
+++ b/tests/qtest/stm32l4x5_usart-test.c
@@ -0,0 +1,325 @@ 
+/*
+ * QTest testcase for STML4X5_USART
+ *
+ * Copyright (c) 2023 Arnaud Minier <arnaud.minier@telecom-paris.fr>
+ * Copyright (c) 2023 Inès Varhol <ines.varhol@telecom-paris.fr>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include "libqtest.h"
+#include "hw/misc/stm32l4x5_rcc_internals.h"
+#include "hw/registerfields.h"
+
+#define RCC_BASE_ADDR 0x40021000
+/* Use USART 1 ADDR, assume the others work the same */
+#define USART1_BASE_ADDR 0x40013800
+
+/* See stm32l4x5_usart for definitions */
+REG32(CR1, 0x00)
+    FIELD(CR1, M1, 28, 1)
+    FIELD(CR1, OVER8, 15, 1)
+    FIELD(CR1, M0, 12, 1)
+    FIELD(CR1, PCE, 10, 1)
+    FIELD(CR1, TXEIE, 7, 1)
+    FIELD(CR1, RXNEIE, 5, 1)
+    FIELD(CR1, TE, 3, 1)
+    FIELD(CR1, RE, 2, 1)
+    FIELD(CR1, UE, 0, 1)
+REG32(CR2, 0x04)
+REG32(CR3, 0x08)
+    FIELD(CR3, OVRDIS, 12, 1)
+REG32(BRR, 0x0C)
+REG32(GTPR, 0x10)
+REG32(RTOR, 0x14)
+REG32(RQR, 0x18)
+REG32(ISR, 0x1C)
+    FIELD(ISR, TXE, 7, 1)
+    FIELD(ISR, RXNE, 5, 1)
+    FIELD(ISR, ORE, 3, 1)
+REG32(ICR, 0x20)
+REG32(RDR, 0x24)
+REG32(TDR, 0x28)
+
+#define NVIC_ISPR1 0XE000E204
+#define NVIC_ICPR1 0xE000E284
+#define USART1_IRQ 37
+
+static bool check_nvic_pending(QTestState *qts, unsigned int n)
+{
+    /* No USART interrupts are less than 32 */
+    assert(n > 32);
+    n -= 32;
+    return qtest_readl(qts, NVIC_ISPR1) & (1 << n);
+}
+
+static bool clear_nvic_pending(QTestState *qts, unsigned int n)
+{
+    /* No USART interrupts are less than 32 */
+    assert(n > 32);
+    n -= 32;
+    qtest_writel(qts, NVIC_ICPR1, (1 << n));
+    return true;
+}
+
+/*
+ * Wait indefinitely for the flag to be updated.
+ * If this is run on a slow CI runner,
+ * the meson harness will timeout after 10 minutes for us.
+ */
+static bool usart_wait_for_flag(QTestState *qts, uint32_t event_addr, uint32_t flag)
+{
+    while (true) {
+        if ((qtest_readl(qts, event_addr) & flag)) {
+            return true;
+        }
+        g_usleep(1000);
+    }
+
+    return false;
+}
+
+static void usart_receive_string(QTestState *qts, int sock_fd, const char *in,
+                           char *out)
+{
+    int i, in_len = strlen(in);
+
+    g_assert_true(send(sock_fd, in, in_len, 0) == in_len);
+    for (i = 0; i < in_len; i++) {
+        g_assert_true(usart_wait_for_flag(qts,
+            USART1_BASE_ADDR + A_ISR, R_ISR_RXNE_MASK));
+        out[i] = qtest_readl(qts, USART1_BASE_ADDR + A_RDR);
+    }
+    out[i] = '\0';
+}
+
+static void usart_send_string(QTestState *qts, const char *in)
+{
+    int i, in_len = strlen(in);
+
+    for (i = 0; i < in_len; i++) {
+        qtest_writel(qts, USART1_BASE_ADDR + A_TDR, in[i]);
+        g_assert_true(usart_wait_for_flag(qts,
+            USART1_BASE_ADDR + A_ISR, R_ISR_TXE_MASK));
+    }
+}
+
+/* Init the RCC clocks to run at 80 MHz */
+static void init_clocks(QTestState *qts)
+{
+    uint32_t value;
+
+    /* MSIRANGE can be set only when MSI is OFF or READY */
+    qtest_writel(qts, (RCC_BASE_ADDR + A_CR), R_CR_MSION_MASK);
+
+    /* Clocking from MSI, in case MSI was not the default source */
+    qtest_writel(qts, (RCC_BASE_ADDR + A_CFGR), 0);
+
+    /*
+     * Update PLL and set MSI as the source clock.
+     * PLLM = 1 --> 000
+     * PLLN = 40 --> 40
+     * PPLLR = 2 --> 00
+     * PLLDIV = unused, PLLP = unused (SAI3), PLLQ = unused (48M1)
+     * SRC = MSI --> 01
+     */
+    qtest_writel(qts, (RCC_BASE_ADDR + A_PLLCFGR), R_PLLCFGR_PLLREN_MASK |
+            (40 << R_PLLCFGR_PLLN_SHIFT) |
+            (0b01 << R_PLLCFGR_PLLSRC_SHIFT));
+
+    /* PLL activation */
+
+    value = qtest_readl(qts, (RCC_BASE_ADDR + A_CR));
+    qtest_writel(qts, (RCC_BASE_ADDR + A_CR), value | R_CR_PLLON_MASK);
+
+    /* RCC_CFGR is OK by defaut */
+    qtest_writel(qts, (RCC_BASE_ADDR + A_CFGR), 0);
+
+    /* CCIPR : no periph clock by default */
+    qtest_writel(qts, (RCC_BASE_ADDR + A_CCIPR), 0);
+
+    /* Switches on the PLL clock source */
+    value = qtest_readl(qts, (RCC_BASE_ADDR + A_CFGR));
+    qtest_writel(qts, (RCC_BASE_ADDR + A_CFGR), (value & ~R_CFGR_SW_MASK) |
+        (0b11 << R_CFGR_SW_SHIFT));
+
+    /* Enable SYSCFG clock enabled */
+    qtest_writel(qts, (RCC_BASE_ADDR + A_APB2ENR), R_APB2ENR_SYSCFGEN_MASK);
+
+    /* Enable the IO port B clock (See p.252) */
+    qtest_writel(qts, (RCC_BASE_ADDR + A_AHB2ENR), R_AHB2ENR_GPIOBEN_MASK);
+
+    /* Enable the clock for USART1 (cf p.259) */
+    /* We rewrite SYSCFGEN to not disable it */
+    qtest_writel(qts, (RCC_BASE_ADDR + A_APB2ENR),
+                 R_APB2ENR_SYSCFGEN_MASK | R_APB2ENR_USART1EN_MASK);
+
+    /* TODO: Enable usart via gpio */
+    /* Set Pin 6 & 7 of port B in Alternate Function mode */
+    /* GPIOB->MODER = (GPIOB->MODER & ~(GPIO_MODER_MODE6_Msk |
+                    GPIO_MODER_MODE7_Msk)) |
+                    (AF_MODE << GPIO_MODER_MODE6_Pos) |
+                    (AF_MODE << GPIO_MODER_MODE7_Pos); */
+
+    /* Specify Alternate Function mode n°7 for Pin 6 & 7 of port B */
+    /* GPIOB->AFR[0] = (GPIOB->AFR[0] & ~(GPIO_AFRL_AFSEL6_Msk |
+                        GPIO_AFRL_AFSEL7_Msk )) |
+                        (AF7 << GPIO_AFRL_AFSEL6_Pos) |
+                        (AF7 << GPIO_AFRL_AFSEL7_Pos); */
+
+    /* Set PCLK as the clock for USART1(cf p.272) i.e. reset both bits */
+    qtest_writel(qts, (RCC_BASE_ADDR + A_CCIPR), 0);
+
+    /* Reset USART1 (see p.249) */
+    qtest_writel(qts, (RCC_BASE_ADDR + A_APB2RSTR), 1 << 14);
+    qtest_writel(qts, (RCC_BASE_ADDR + A_APB2RSTR), 0);
+}
+
+static void init_uart(QTestState *qts)
+{
+    uint32_t cr1;
+
+    init_clocks(qts);
+
+    /*
+     * For 115200 bauds, see p.1349.
+     * The clock has a frequency of 80Mhz,
+     * for 115200, we have to put a divider of 695 = 0x2B7.
+     */
+    qtest_writel(qts, (USART1_BASE_ADDR + A_BRR), 0x2B7);
+
+    /*
+     * Set the oversampling by 16,
+     * disable the parity control and
+     * set the word length to 8. (cf p.1377)
+     */
+    cr1 = qtest_readl(qts, (USART1_BASE_ADDR + A_CR1));
+    cr1 &= ~(R_CR1_M1_MASK | R_CR1_M0_MASK | R_CR1_OVER8_MASK | R_CR1_PCE_MASK);
+    qtest_writel(qts, (USART1_BASE_ADDR + A_CR1), cr1);
+
+    /* Enable the transmitter, the receiver and the USART. */
+    qtest_writel(qts, (USART1_BASE_ADDR + A_CR1),
+        R_CR1_UE_MASK | R_CR1_RE_MASK | R_CR1_TE_MASK);
+}
+
+static void test_write_read(void)
+{
+    QTestState *qts = qtest_init("-M b-l475e-iot01a");
+
+    /* Test that we can write and retrieve a value from the device */
+    qtest_writel(qts, USART1_BASE_ADDR + A_TDR, 0xFFFFFFFF);
+    const uint32_t tdr = qtest_readl(qts, USART1_BASE_ADDR + A_TDR);
+    g_assert_cmpuint(tdr, ==, 0x000001FF);
+}
+
+static void test_receive_char(void)
+{
+    int sock_fd;
+    uint32_t cr1;
+    QTestState *qts = qtest_init_with_serial("-M b-l475e-iot01a", &sock_fd);
+
+    init_uart(qts);
+
+    /* Try without initializing IRQ */
+    g_assert_true(send(sock_fd, "a", 1, 0) == 1);
+    usart_wait_for_flag(qts, USART1_BASE_ADDR + A_ISR, R_ISR_RXNE_MASK);
+    g_assert_cmphex(qtest_readl(qts, USART1_BASE_ADDR + A_RDR), ==, 'a');
+    g_assert_false(check_nvic_pending(qts, USART1_IRQ));
+
+    /* Now with the IRQ */
+    cr1 = qtest_readl(qts, (USART1_BASE_ADDR + A_CR1));
+    cr1 |= R_CR1_RXNEIE_MASK;
+    qtest_writel(qts, USART1_BASE_ADDR + A_CR1, cr1);
+    g_assert_true(send(sock_fd, "b", 1, 0) == 1);
+    usart_wait_for_flag(qts, USART1_BASE_ADDR + A_ISR, R_ISR_RXNE_MASK);
+    g_assert_cmphex(qtest_readl(qts, USART1_BASE_ADDR + A_RDR), ==, 'b');
+    g_assert_true(check_nvic_pending(qts, USART1_IRQ));
+    clear_nvic_pending(qts, USART1_IRQ);
+
+    close(sock_fd);
+
+    qtest_quit(qts);
+}
+
+static void test_send_char(void)
+{
+    int sock_fd;
+    char s[1];
+    uint32_t cr1;
+    QTestState *qts = qtest_init_with_serial("-M b-l475e-iot01a", &sock_fd);
+
+    init_uart(qts);
+
+    /* Try without initializing IRQ */
+    qtest_writel(qts, USART1_BASE_ADDR + A_TDR, 'c');
+    g_assert_true(recv(sock_fd, s, 1, 0) == 1);
+    g_assert_cmphex(s[0], ==, 'c');
+    g_assert_false(check_nvic_pending(qts, USART1_IRQ));
+
+    /* Now with the IRQ */
+    cr1 = qtest_readl(qts, (USART1_BASE_ADDR + A_CR1));
+    cr1 |= R_CR1_TXEIE_MASK;
+    qtest_writel(qts, USART1_BASE_ADDR + A_CR1, cr1);
+    qtest_writel(qts, USART1_BASE_ADDR + A_TDR, 'd');
+    g_assert_true(recv(sock_fd, s, 1, 0) == 1);
+    g_assert_cmphex(s[0], ==, 'd');
+    g_assert_true(check_nvic_pending(qts, USART1_IRQ));
+    clear_nvic_pending(qts, USART1_IRQ);
+
+    close(sock_fd);
+
+    qtest_quit(qts);
+}
+
+static void test_receive_str(void)
+{
+    int sock_fd;
+    char s[10];
+    QTestState *qts = qtest_init_with_serial("-M b-l475e-iot01a", &sock_fd);
+
+    init_uart(qts);
+
+    usart_receive_string(qts, sock_fd, "hello", s);
+    g_assert_true(memcmp(s, "hello", 5) == 0);
+
+    close(sock_fd);
+
+    qtest_quit(qts);
+}
+
+static void test_send_str(void)
+{
+    int sock_fd;
+    char s[10];
+    QTestState *qts = qtest_init_with_serial("-M b-l475e-iot01a", &sock_fd);
+
+    init_uart(qts);
+
+    usart_send_string(qts, "world");
+    g_assert_true(recv(sock_fd, s, 10, 0) == 5);
+    g_assert_true(memcmp(s, "world", 5) == 0);
+
+    close(sock_fd);
+
+    qtest_quit(qts);
+}
+
+int main(int argc, char **argv)
+{
+    int ret;
+
+    g_test_init(&argc, &argv, NULL);
+    g_test_set_nonfatal_assertions();
+
+    qtest_add_func("stm32l4x5/usart/write_read", test_write_read);
+    qtest_add_func("stm32l4x5/usart/receive_char", test_receive_char);
+    qtest_add_func("stm32l4x5/usart/send_char", test_send_char);
+    qtest_add_func("stm32l4x5/usart/receive_str", test_receive_str);
+    qtest_add_func("stm32l4x5/usart/send_str", test_send_str);
+    ret = g_test_run();
+
+    return ret;
+}
+