serial: 8250_pci: add support for Intel BayTrail

Intel BayTrail has two HS-UARTs with 64 byte fifo, support
for DMA and support for 16750 compatible Auto Flow Control.
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/8250/8250_pci.c

@@ -1324,6 +1324,120 @@ ce4100_serial_setup(struct serial_private *priv,
 	return ret;
 }
 
+#define PCI_DEVICE_ID_INTEL_BYT_UART1	0x0f0a
+#define PCI_DEVICE_ID_INTEL_BYT_UART2	0x0f0c
+
+#define BYT_PRV_CLK			0x800
+#define BYT_PRV_CLK_EN			(1 << 0)
+#define BYT_PRV_CLK_M_VAL_SHIFT		1
+#define BYT_PRV_CLK_N_VAL_SHIFT		16
+#define BYT_PRV_CLK_UPDATE		(1 << 31)
+
+#define BYT_GENERAL_REG			0x808
+#define BYT_GENERAL_DIS_RTS_N_OVERRIDE	(1 << 3)
+
+#define BYT_TX_OVF_INT			0x820
+#define BYT_TX_OVF_INT_MASK		(1 << 1)
+
+static void
+byt_set_termios(struct uart_port *p, struct ktermios *termios,
+		struct ktermios *old)
+{
+	unsigned int baud = tty_termios_baud_rate(termios);
+	unsigned int m = 6912;
+	unsigned int n = 15625;
+	u32 reg;
+
+	/* For baud rates 1M, 2M, 3M and 4M the dividers must be adjusted. */
+	if (baud == 1000000 || baud == 2000000 || baud == 4000000) {
+		m = 64;
+		n = 100;
+
+		p->uartclk = 64000000;
+	} else if (baud == 3000000) {
+		m = 48;
+		n = 100;
+
+		p->uartclk = 48000000;
+	} else {
+		p->uartclk = 44236800;
+	}
+
+	/* Reset the clock */
+	reg = (m << BYT_PRV_CLK_M_VAL_SHIFT) | (n << BYT_PRV_CLK_N_VAL_SHIFT);
+	writel(reg, p->membase + BYT_PRV_CLK);
+	reg |= BYT_PRV_CLK_EN | BYT_PRV_CLK_UPDATE;
+	writel(reg, p->membase + BYT_PRV_CLK);
+
+	/*
+	 * If auto-handshake mechanism is not enabled,
+	 * disable rts_n override
+	 */
+	reg = readl(p->membase + BYT_GENERAL_REG);
+	reg &= ~BYT_GENERAL_DIS_RTS_N_OVERRIDE;
+	if (termios->c_cflag & CRTSCTS)
+		reg |= BYT_GENERAL_DIS_RTS_N_OVERRIDE;
+	writel(reg, p->membase + BYT_GENERAL_REG);
+
+	serial8250_do_set_termios(p, termios, old);
+}
+
+static bool byt_dma_filter(struct dma_chan *chan, void *param)
+{
+	return chan->chan_id == *(int *)param;
+}
+
+static int
+byt_serial_setup(struct serial_private *priv,
+		 const struct pciserial_board *board,
+		 struct uart_8250_port *port, int idx)
+{
+	struct uart_8250_dma *dma;
+	int ret;
+
+	dma = devm_kzalloc(port->port.dev, sizeof(*dma), GFP_KERNEL);
+	if (!dma)
+		return -ENOMEM;
+
+	switch (priv->dev->device) {
+	case PCI_DEVICE_ID_INTEL_BYT_UART1:
+		dma->rx_chan_id = 3;
+		dma->tx_chan_id = 2;
+		break;
+	case PCI_DEVICE_ID_INTEL_BYT_UART2:
+		dma->rx_chan_id = 5;
+		dma->tx_chan_id = 4;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	dma->rxconf.slave_id = dma->rx_chan_id;
+	dma->rxconf.src_maxburst = 16;
+
+	dma->txconf.slave_id = dma->tx_chan_id;
+	dma->txconf.dst_maxburst = 16;
+
+	dma->fn = byt_dma_filter;
+	dma->rx_param = &dma->rx_chan_id;
+	dma->tx_param = &dma->tx_chan_id;
+
+	ret = pci_default_setup(priv, board, port, idx);
+	port->port.iotype = UPIO_MEM;
+	port->port.type = PORT_16550A;
+	port->port.flags = (port->port.flags | UPF_FIXED_PORT | UPF_FIXED_TYPE);
+	port->port.set_termios = byt_set_termios;
+	port->port.fifosize = 64;
+	port->tx_loadsz = 64;
+	port->dma = dma;
+	port->capabilities = UART_CAP_FIFO | UART_CAP_AFE;
+
+	/* Disable Tx counter interrupts */
+	writel(BYT_TX_OVF_INT_MASK, port->port.membase + BYT_TX_OVF_INT);
+
+	return ret;
+}
+
 static int
 pci_omegapci_setup(struct serial_private *priv,
 		      const struct pciserial_board *board,
@@ -1662,6 +1776,20 @@ static struct pci_serial_quirk pci_serial_quirks[] __refdata = {
 		.subdevice	= PCI_ANY_ID,
 		.setup		= kt_serial_setup,
 	},
+	{
+		.vendor		= PCI_VENDOR_ID_INTEL,
+		.device		= PCI_DEVICE_ID_INTEL_BYT_UART1,
+		.subvendor	= PCI_ANY_ID,
+		.subdevice	= PCI_ANY_ID,
+		.setup		= byt_serial_setup,
+	},
+	{
+		.vendor		= PCI_VENDOR_ID_INTEL,
+		.device		= PCI_DEVICE_ID_INTEL_BYT_UART2,
+		.subvendor	= PCI_ANY_ID,
+		.subdevice	= PCI_ANY_ID,
+		.setup		= byt_serial_setup,
+	},
 	/*
 	 * ITE
 	 */
@@ -2449,6 +2577,7 @@ enum pci_board_num_t {
 	pbn_ADDIDATA_PCIe_4_3906250,
 	pbn_ADDIDATA_PCIe_8_3906250,
 	pbn_ce4100_1_115200,
+	pbn_byt,
 	pbn_omegapci,
 	pbn_NETMOS9900_2s_115200,
 	pbn_brcm_trumanage,
@@ -3185,6 +3314,13 @@ static struct pciserial_board pci_boards[] = {
 		.base_baud	= 921600,
 		.reg_shift      = 2,
 	},
+	[pbn_byt] = {
+		.flags		= FL_BASE0,
+		.num_ports	= 1,
+		.base_baud	= 2764800,
+		.uart_offset	= 0x80,
+		.reg_shift      = 2,
+	},
 	[pbn_omegapci] = {
 		.flags		= FL_BASE0,
 		.num_ports	= 8,
@@ -4846,6 +4982,15 @@ static struct pci_device_id serial_pci_tbl[] = {
 	{	PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_CE4100_UART,
 		PCI_ANY_ID,  PCI_ANY_ID, 0, 0,
 		pbn_ce4100_1_115200 },
+	/* Intel BayTrail */
+	{	PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_BYT_UART1,
+		PCI_ANY_ID,  PCI_ANY_ID,
+		PCI_CLASS_COMMUNICATION_SERIAL << 8, 0xff0000,
+		pbn_byt },
+	{	PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_BYT_UART2,
+		PCI_ANY_ID,  PCI_ANY_ID,
+		PCI_CLASS_COMMUNICATION_SERIAL << 8, 0xff0000,
+		pbn_byt },
 
 	/*
 	 * Cronyx Omega PCI