lib:platform: Fix sbi_getc return type.

As per the current SBI specification, sbi_getc should return
an int instead of char.

In case of FIFO is empty, return -1 as per the specification.

Reported-by: Sergi Granell <xerpi.g.12@gmail.com>
Suggested-by:Thadeu Lima de Souza Cascardo <cascardo@cascardo.eti.br>
Signed-off-by: Atish Patra <atish.patra@wdc.com>

include/sbi/sbi_console.h

@@ -16,7 +16,7 @@
 
 bool sbi_isprintable(char ch);
 
-char sbi_getc(void);
+int sbi_getc(void);
 
 void sbi_putc(char ch);
 

include/sbi/sbi_platform.h

@@ -77,7 +77,7 @@ struct sbi_platform {
 	/** Write a character to the platform console output */
 	void (*console_putc)(char ch);
 	/** Read a character from the platform console input */
-	char (*console_getc)(void);
+	int (*console_getc)(void);
 	/** Initialize the platform console */
 	int (*console_init)(void);
 
@@ -283,11 +283,11 @@ static inline void sbi_platform_console_putc(struct sbi_platform *plat,
  *
  * @return character read from console input
  */
-static inline char sbi_platform_console_getc(struct sbi_platform *plat)
+static inline int sbi_platform_console_getc(struct sbi_platform *plat)
 {
 	if (plat && plat->console_getc)
 		return plat->console_getc();
-	return 0;
+	return -1;
 }
 
 /**

lib/sbi_console.c

@@ -26,7 +26,7 @@ bool sbi_isprintable(char c)
 	return FALSE;
 }
 
-char sbi_getc(void)
+int sbi_getc(void)
 {
 	return sbi_platform_console_getc(console_plat);
 }
@@ -50,10 +50,11 @@ void sbi_puts(const char *str)
 
 void sbi_gets(char *s, int maxwidth, char endchar)
 {
-	char ch, *retval = s;
+	int ch;
+	char *retval = s;
 
-	while ((ch = sbi_getc()) != endchar && maxwidth > 1) {
-		*retval = ch;
+	while ((ch = sbi_getc()) != endchar && ch >= 0 && maxwidth > 1) {
+		*retval = (char) ch;
 		retval++;
 		maxwidth--;
 	}

platform/common/include/plat/serial/sifive-uart.h

@@ -14,7 +14,7 @@
 
 void sifive_uart_putc(char ch);
 
-char sifive_uart_getc(void);
+int sifive_uart_getc(void);
 
 int sifive_uart_init(unsigned long base,
 		     u32 in_freq, u32 baudrate);

platform/common/include/plat/serial/uart8250.h

@@ -14,7 +14,7 @@
 
 void uart8250_putc(char ch);
 
-char uart8250_getc(void);
+int uart8250_getc(void);
 
 int uart8250_init(unsigned long base,
 		  u32 in_freq, u32 baudrate,

platform/common/serial/sifive-uart.c

@@ -69,12 +69,12 @@ void sifive_uart_putc(char ch)
 	set_reg(UART_REG_TXFIFO, ch);
 }
 
-char sifive_uart_getc(void)
+int sifive_uart_getc(void)
 {
 	u32 ret = get_reg(UART_REG_RXFIFO);
 	if (!(ret & UART_RXFIFO_EMPTY))
 		return ret & UART_RXFIFO_DATA;
-	return 0;
+	return -1;
 }
 
 int sifive_uart_init(unsigned long base,

platform/common/serial/uart8250.c

@@ -71,11 +71,11 @@ void uart8250_putc(char ch)
 	set_reg(UART_THR_OFFSET, ch);
 }
 
-char uart8250_getc(void)
+int uart8250_getc(void)
 {
 	if (get_reg(UART_LSR_OFFSET) & UART_LSR_DR)
 		return get_reg(UART_RBR_OFFSET);
-	return 0;
+	return -1;
 }
 
 int uart8250_init(unsigned long base,

platform/kendryte/k210/platform.c

@@ -31,7 +31,7 @@ static void k210_console_putc(char c)
 	uarths_putc(c);
 }
 
-static char k210_console_getc(void)
+static int k210_console_getc(void)
 {
 	return uarths_getc();
 }

platform/kendryte/k210/uarths.c

@@ -48,12 +48,12 @@ void uarths_putc(char c)
 	uarths->txdata.data = (u8)c;
 }
 
-char uarths_getc(void)
+int uarths_getc(void)
 {
 	struct uarths_rxdata rx = uarths->rxdata;
 
 	if (rx.empty)
-		return '\0';
+		return -1;
 
 	return rx.data;
 }

platform/kendryte/k210/uarths.h

@@ -161,6 +161,6 @@ enum uarths_stopbit {
 
 void uarths_init(u32 baud_rate, enum uarths_stopbit stopbit);
 void uarths_putc(char c);
-char uarths_getc(void);
+int uarths_getc(void);
 
 #endif /* _K210_UARTHS_H_ */

platform/template/platform.c

@@ -73,7 +73,7 @@ static void platform_console_putc(char ch)
 /*
  * Read a character from the platform console input.
  */
-static char platform_console_getc(void)
+static int platform_console_getc(void)
 {
 	return uart8250_getc();
 }