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serial: stm32: add support for RS485 hardware control mode
Implement Driver Enable signal (DE) to activate the transmission mode of the external transceiver. Signed-off-by: Yves Coppeaux <yves.coppeaux@st.com> Signed-off-by: Bich Hemon <bich.hemon@st.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Bich HEMON
Greg Kroah-Hartman
parent
241672cb4b
commit
1bcda09d29
@ -62,6 +62,113 @@ static void stm32_clr_bits(struct uart_port *port, u32 reg, u32 bits)
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writel_relaxed(val, port->membase + reg);
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}
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static void stm32_config_reg_rs485(u32 *cr1, u32 *cr3, u32 delay_ADE,
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u32 delay_DDE, u32 baud)
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{
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u32 rs485_deat_dedt;
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u32 rs485_deat_dedt_max = (USART_CR1_DEAT_MASK >> USART_CR1_DEAT_SHIFT);
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bool over8;
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*cr3 |= USART_CR3_DEM;
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over8 = *cr1 & USART_CR1_OVER8;
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if (over8)
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rs485_deat_dedt = delay_ADE * baud * 8;
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else
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rs485_deat_dedt = delay_ADE * baud * 16;
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rs485_deat_dedt = DIV_ROUND_CLOSEST(rs485_deat_dedt, 1000);
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rs485_deat_dedt = rs485_deat_dedt > rs485_deat_dedt_max ?
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rs485_deat_dedt_max : rs485_deat_dedt;
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rs485_deat_dedt = (rs485_deat_dedt << USART_CR1_DEAT_SHIFT) &
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USART_CR1_DEAT_MASK;
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*cr1 |= rs485_deat_dedt;
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if (over8)
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rs485_deat_dedt = delay_DDE * baud * 8;
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else
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rs485_deat_dedt = delay_DDE * baud * 16;
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rs485_deat_dedt = DIV_ROUND_CLOSEST(rs485_deat_dedt, 1000);
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rs485_deat_dedt = rs485_deat_dedt > rs485_deat_dedt_max ?
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rs485_deat_dedt_max : rs485_deat_dedt;
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rs485_deat_dedt = (rs485_deat_dedt << USART_CR1_DEDT_SHIFT) &
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USART_CR1_DEDT_MASK;
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*cr1 |= rs485_deat_dedt;
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}
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static int stm32_config_rs485(struct uart_port *port,
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struct serial_rs485 *rs485conf)
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{
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struct stm32_port *stm32_port = to_stm32_port(port);
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struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
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struct stm32_usart_config *cfg = &stm32_port->info->cfg;
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u32 usartdiv, baud, cr1, cr3;
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bool over8;
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unsigned long flags;
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spin_lock_irqsave(&port->lock, flags);
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stm32_clr_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit));
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port->rs485 = *rs485conf;
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rs485conf->flags |= SER_RS485_RX_DURING_TX;
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if (rs485conf->flags & SER_RS485_ENABLED) {
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cr1 = readl_relaxed(port->membase + ofs->cr1);
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cr3 = readl_relaxed(port->membase + ofs->cr3);
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usartdiv = readl_relaxed(port->membase + ofs->brr);
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usartdiv = usartdiv & GENMASK(15, 0);
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over8 = cr1 & USART_CR1_OVER8;
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if (over8)
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usartdiv = usartdiv | (usartdiv & GENMASK(4, 0))
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<< USART_BRR_04_R_SHIFT;
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baud = DIV_ROUND_CLOSEST(port->uartclk, usartdiv);
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stm32_config_reg_rs485(&cr1, &cr3,
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rs485conf->delay_rts_before_send,
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rs485conf->delay_rts_after_send, baud);
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if (rs485conf->flags & SER_RS485_RTS_ON_SEND) {
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cr3 &= ~USART_CR3_DEP;
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rs485conf->flags &= ~SER_RS485_RTS_AFTER_SEND;
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} else {
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cr3 |= USART_CR3_DEP;
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rs485conf->flags |= SER_RS485_RTS_AFTER_SEND;
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}
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writel_relaxed(cr3, port->membase + ofs->cr3);
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writel_relaxed(cr1, port->membase + ofs->cr1);
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} else {
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stm32_clr_bits(port, ofs->cr3, USART_CR3_DEM | USART_CR3_DEP);
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stm32_clr_bits(port, ofs->cr1,
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USART_CR1_DEDT_MASK | USART_CR1_DEAT_MASK);
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}
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stm32_set_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit));
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spin_unlock_irqrestore(&port->lock, flags);
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return 0;
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}
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static int stm32_init_rs485(struct uart_port *port,
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struct platform_device *pdev)
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{
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struct serial_rs485 *rs485conf = &port->rs485;
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rs485conf->flags = 0;
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rs485conf->delay_rts_before_send = 0;
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rs485conf->delay_rts_after_send = 0;
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if (!pdev->dev.of_node)
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return -ENODEV;
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uart_get_rs485_mode(&pdev->dev, rs485conf);
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return 0;
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}
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static int stm32_pending_rx(struct uart_port *port, u32 *sr, int *last_res,
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bool threaded)
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{
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@ -498,6 +605,7 @@ static void stm32_set_termios(struct uart_port *port, struct ktermios *termios,
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struct stm32_port *stm32_port = to_stm32_port(port);
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struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
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struct stm32_usart_config *cfg = &stm32_port->info->cfg;
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struct serial_rs485 *rs485conf = &port->rs485;
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unsigned int baud;
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u32 usartdiv, mantissa, fraction, oversampling;
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tcflag_t cflag = termios->c_cflag;
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@ -515,7 +623,7 @@ static void stm32_set_termios(struct uart_port *port, struct ktermios *termios,
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writel_relaxed(0, port->membase + ofs->cr1);
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cr1 = USART_CR1_TE | USART_CR1_RE | USART_CR1_RXNEIE;
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cr1 |= BIT(cfg->uart_enable_bit);
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if (stm32_port->fifoen)
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cr1 |= USART_CR1_FIFOEN;
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cr2 = 0;
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@ -553,9 +661,11 @@ static void stm32_set_termios(struct uart_port *port, struct ktermios *termios,
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*/
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if (usartdiv < 16) {
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oversampling = 8;
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cr1 |= USART_CR1_OVER8;
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stm32_set_bits(port, ofs->cr1, USART_CR1_OVER8);
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} else {
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oversampling = 16;
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cr1 &= ~USART_CR1_OVER8;
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stm32_clr_bits(port, ofs->cr1, USART_CR1_OVER8);
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}
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@ -592,10 +702,28 @@ static void stm32_set_termios(struct uart_port *port, struct ktermios *termios,
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if (stm32_port->rx_ch)
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cr3 |= USART_CR3_DMAR;
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if (rs485conf->flags & SER_RS485_ENABLED) {
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stm32_config_reg_rs485(&cr1, &cr3,
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rs485conf->delay_rts_before_send,
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rs485conf->delay_rts_after_send, baud);
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if (rs485conf->flags & SER_RS485_RTS_ON_SEND) {
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cr3 &= ~USART_CR3_DEP;
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rs485conf->flags &= ~SER_RS485_RTS_AFTER_SEND;
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} else {
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cr3 |= USART_CR3_DEP;
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rs485conf->flags |= SER_RS485_RTS_AFTER_SEND;
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}
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} else {
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cr3 &= ~(USART_CR3_DEM | USART_CR3_DEP);
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cr1 &= ~(USART_CR1_DEDT_MASK | USART_CR1_DEAT_MASK);
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}
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writel_relaxed(cr3, port->membase + ofs->cr3);
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writel_relaxed(cr2, port->membase + ofs->cr2);
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writel_relaxed(cr1, port->membase + ofs->cr1);
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stm32_set_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit));
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spin_unlock_irqrestore(&port->lock, flags);
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}
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@ -135,6 +135,7 @@ struct stm32_usart_info stm32h7_info = {
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#define USART_BRR_DIV_F_MASK GENMASK(3, 0)
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#define USART_BRR_DIV_M_MASK GENMASK(15, 4)
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#define USART_BRR_DIV_M_SHIFT 4
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#define USART_BRR_04_R_SHIFT 1
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/* USART_CR1 */
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#define USART_CR1_SBK BIT(0)
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@ -162,6 +163,8 @@ struct stm32_usart_info stm32h7_info = {
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#define USART_CR1_M1 BIT(28) /* F7 */
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#define USART_CR1_IE_MASK (GENMASK(8, 4) | BIT(14) | BIT(26) | BIT(27))
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#define USART_CR1_FIFOEN BIT(29) /* H7 */
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#define USART_CR1_DEAT_SHIFT 21
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#define USART_CR1_DEDT_SHIFT 16
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/* USART_CR2 */
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#define USART_CR2_ADD_MASK GENMASK(3, 0) /* F4 */
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