From 5644bf1843d915b6fb460fd44f4b9f9ac19a3fbb Mon Sep 17 00:00:00 2001 From: Sergiu Moga Date: Thu, 22 Sep 2022 14:33:45 +0300 Subject: tty: serial: atmel: Only divide Clock Divisor if the IP is USART MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Make sure that the driver only divides the clock divisor if the IP handled at that point is USART, since UART IP's do not support implicit peripheral clock division. Instead, in the case of UART, go with the highest possible clock divisor. Signed-off-by: Sergiu Moga Reviewed-by: Ilpo Järvinen Link: https://lore.kernel.org/r/20220922113347.144383-8-sergiu.moga@microchip.com Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/atmel_serial.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) (limited to 'drivers/tty/serial/atmel_serial.c') diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c index e3e14cb7668b..acbf6b82d687 100644 --- a/drivers/tty/serial/atmel_serial.c +++ b/drivers/tty/serial/atmel_serial.c @@ -150,6 +150,7 @@ struct atmel_uart_port { u32 rts_low; bool ms_irq_enabled; u32 rtor; /* address of receiver timeout register if it exists */ + bool is_usart; bool has_frac_baudrate; bool has_hw_timer; struct timer_list uart_timer; @@ -1825,6 +1826,7 @@ static void atmel_get_ip_name(struct uart_port *port) */ atmel_port->has_frac_baudrate = false; atmel_port->has_hw_timer = false; + atmel_port->is_usart = false; if (name == new_uart) { dev_dbg(port->dev, "Uart with hw timer"); @@ -1834,6 +1836,7 @@ static void atmel_get_ip_name(struct uart_port *port) dev_dbg(port->dev, "Usart\n"); atmel_port->has_frac_baudrate = true; atmel_port->has_hw_timer = true; + atmel_port->is_usart = true; atmel_port->rtor = ATMEL_US_RTOR; version = atmel_uart_readl(port, ATMEL_US_VERSION); switch (version) { @@ -1863,6 +1866,7 @@ static void atmel_get_ip_name(struct uart_port *port) dev_dbg(port->dev, "This version is usart\n"); atmel_port->has_frac_baudrate = true; atmel_port->has_hw_timer = true; + atmel_port->is_usart = true; atmel_port->rtor = ATMEL_US_RTOR; break; case 0x203: @@ -2286,10 +2290,21 @@ static void atmel_set_termios(struct uart_port *port, cd = uart_get_divisor(port, baud); } - if (cd > 65535) { /* BRGR is 16-bit, so switch to slower clock */ + /* + * If the current value of the Clock Divisor surpasses the 16 bit + * ATMEL_US_CD mask and the IP is USART, switch to the Peripheral + * Clock implicitly divided by 8. + * If the IP is UART however, keep the highest possible value for + * the CD and avoid needless division of CD, since UART IP's do not + * support implicit division of the Peripheral Clock. + */ + if (atmel_port->is_usart && cd > ATMEL_US_CD) { cd /= 8; mode |= ATMEL_US_USCLKS_MCK_DIV8; + } else { + cd = min_t(unsigned int, cd, ATMEL_US_CD); } + quot = cd | fp << ATMEL_US_FP_OFFSET; if (!(port->iso7816.flags & SER_ISO7816_ENABLED)) -- cgit v1.2.3