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>

1 files changed, 145 insertions, 0 deletions

diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c
index 515fd0ff4e4e..d917bbb30484 100644
--- a/drivers/tty/serial/8250/8250_pci.c
+++ b/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