diff options
author | Erwan Le Ray <erwan.leray@st.com> | 2019-06-18 12:02:24 +0200 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-06-21 11:17:36 +0200 |
commit | d075719e62ae7bc7fed3ff5be365c8c384483f15 (patch) | |
tree | f46fa9a3deb6d5d15999bec5ab7f5912620ce4d8 /drivers/tty/serial/stm32-usart.c | |
parent | 5d9176edacc29cadb9a0b52c8aaba67ce5ff4ed4 (diff) | |
download | linux-d075719e62ae7bc7fed3ff5be365c8c384483f15.tar.bz2 |
serial: stm32: add support of TX FIFO threshold
Adds the support of TX FIFO threshold in order to improve the TX FIFO
management:
- TX FIFO threshold irq enabling (instead of relying on tx empty / fifo
not full irq that generates one irq/char)
- TXCFG is set to half fifo size (e.g. 16/2 = 8 data for a 16 data depth
FIFO)
- irq rate may be reduced by up to 1/TXCFG, e.g. 1 over 8 with current
TXCFG setting.
Signed-off-by: Erwan Le Ray <erwan.leray@st.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/serial/stm32-usart.c')
-rw-r--r-- | drivers/tty/serial/stm32-usart.c | 51 |
1 files changed, 42 insertions, 9 deletions
diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c index 2085f10aabfa..959f33bb0eb6 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -295,6 +295,32 @@ static void stm32_tx_dma_complete(void *arg) stm32_transmit_chars(port); } +static void stm32_tx_interrupt_enable(struct uart_port *port) +{ + struct stm32_port *stm32_port = to_stm32_port(port); + struct stm32_usart_offsets *ofs = &stm32_port->info->ofs; + + /* + * Enables TX FIFO threashold irq when FIFO is enabled, + * or TX empty irq when FIFO is disabled + */ + if (stm32_port->fifoen) + stm32_set_bits(port, ofs->cr3, USART_CR3_TXFTIE); + else + stm32_set_bits(port, ofs->cr1, USART_CR1_TXEIE); +} + +static void stm32_tx_interrupt_disable(struct uart_port *port) +{ + struct stm32_port *stm32_port = to_stm32_port(port); + struct stm32_usart_offsets *ofs = &stm32_port->info->ofs; + + if (stm32_port->fifoen) + stm32_clr_bits(port, ofs->cr3, USART_CR3_TXFTIE); + else + stm32_clr_bits(port, ofs->cr1, USART_CR1_TXEIE); +} + static void stm32_transmit_chars_pio(struct uart_port *port) { struct stm32_port *stm32_port = to_stm32_port(port); @@ -317,9 +343,9 @@ static void stm32_transmit_chars_pio(struct uart_port *port) /* rely on TXE irq (mask or unmask) for sending remaining data */ if (uart_circ_empty(xmit)) - stm32_clr_bits(port, ofs->cr1, USART_CR1_TXEIE); + stm32_tx_interrupt_disable(port); else - stm32_set_bits(port, ofs->cr1, USART_CR1_TXEIE); + stm32_tx_interrupt_enable(port); } static void stm32_transmit_chars_dma(struct uart_port *port) @@ -401,7 +427,7 @@ static void stm32_transmit_chars(struct uart_port *port) } if (uart_circ_empty(xmit) || uart_tx_stopped(port)) { - stm32_clr_bits(port, ofs->cr1, USART_CR1_TXEIE); + stm32_tx_interrupt_disable(port); return; } @@ -419,7 +445,7 @@ static void stm32_transmit_chars(struct uart_port *port) uart_write_wakeup(port); if (uart_circ_empty(xmit)) - stm32_clr_bits(port, ofs->cr1, USART_CR1_TXEIE); + stm32_tx_interrupt_disable(port); } static irqreturn_t stm32_interrupt(int irq, void *ptr) @@ -498,10 +524,7 @@ static unsigned int stm32_get_mctrl(struct uart_port *port) /* Transmit stop */ static void stm32_stop_tx(struct uart_port *port) { - struct stm32_port *stm32_port = to_stm32_port(port); - struct stm32_usart_offsets *ofs = &stm32_port->info->ofs; - - stm32_clr_bits(port, ofs->cr1, USART_CR1_TXEIE); + stm32_tx_interrupt_disable(port); } /* There are probably characters waiting to be transmitted. */ @@ -572,6 +595,13 @@ static int stm32_startup(struct uart_port *port) val |= USART_CR1_FIFOEN; stm32_set_bits(port, ofs->cr1, val); + if (stm32_port->fifoen) { + val = readl_relaxed(port->membase + ofs->cr3); + val &= ~USART_CR3_TXFTCFG_MASK; + val |= USART_CR3_TXFTCFG_HALF << USART_CR3_TXFTCFG_SHIFT; + writel_relaxed(val, port->membase + ofs->cr3); + } + return 0; } @@ -659,7 +689,9 @@ static void stm32_set_termios(struct uart_port *port, struct ktermios *termios, if (stm32_port->fifoen) cr1 |= USART_CR1_FIFOEN; cr2 = 0; - cr3 = 0; + cr3 = readl_relaxed(port->membase + ofs->cr3); + cr3 &= USART_CR3_TXFTIE | USART_CR3_RXFTCFG | USART_CR3_RXFTIE + | USART_CR3_TXFTCFG_MASK; if (cflag & CSTOPB) cr2 |= USART_CR2_STOP_2B; @@ -866,6 +898,7 @@ static int stm32_init_port(struct stm32_port *stm32port, port->flags = UPF_BOOT_AUTOCONF; port->ops = &stm32_uart_ops; port->dev = &pdev->dev; + port->fifosize = stm32port->info->cfg.fifosize; ret = platform_get_irq(pdev, 0); if (ret <= 0) { |