feat(drivers/st/uart): add uart driver for STM32MP1

Add a UART/USART driver for STM32 with complete a hardware support;
it used for STM32CubeProgrammer support with even parity.

This driver is not used for console, which is already handle
by a simple driver (drivers/st/uart/aarch32/stm32_console.S).

Change-Id: Ia9266e5d177fe7fd09c8a15b81da1a05b1bc8b2d
Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Signed-off-by: Nicolas Le Bayon <nicolas.le.bayon@st.com>
diff --git a/drivers/st/clk/stm32mp_clkfunc.c b/drivers/st/clk/stm32mp_clkfunc.c
index d57f120..0db0dee 100644
--- a/drivers/st/clk/stm32mp_clkfunc.c
+++ b/drivers/st/clk/stm32mp_clkfunc.c
@@ -14,6 +14,7 @@
 #include <drivers/st/stm32_gpio.h>
 #include <drivers/st/stm32mp_clkfunc.h>
 
+#define DT_UART_COMPAT		"st,stm32h7-uart"
 /*
  * Get the frequency of an oscillator from its name in device tree.
  * @param name: oscillator name
@@ -297,3 +298,32 @@
 	cuint++;
 	return (int)fdt32_to_cpu(*cuint);
 }
+
+/*
+ * Get the frequency of the specified UART instance.
+ * @param instance: UART interface registers base address.
+ * @return: clock frequency on success, 0 value on failure.
+ */
+unsigned long fdt_get_uart_clock_freq(uintptr_t instance)
+{
+	void *fdt;
+	int node;
+	int clk_id;
+
+	if (fdt_get_address(&fdt) == 0) {
+		return 0UL;
+	}
+
+	/* Check for UART nodes */
+	node = dt_match_instance_by_compatible(DT_UART_COMPAT, instance);
+	if (node < 0) {
+		return 0UL;
+	}
+
+	clk_id = fdt_get_clock_id(node);
+	if (clk_id < 0) {
+		return 0UL;
+	}
+
+	return stm32mp_clk_get_rate((unsigned long)clk_id);
+}