drivers/serial/serial_uniphier.c

   1 /*
   2  * Copyright (C) 2012-2015 Panasonic Corporation
   3  * Copyright (C) 2015-2016 Socionext Inc.
   4  *   Author: Masahiro Yamada <yamada.masahiro@socionext.com>
   5  *
   6  * SPDX-License-Identifier:     GPL-2.0+
   7  */
   8
   9 #include <linux/io.h>
  10 #include <linux/serial_reg.h>
  11 #include <linux/sizes.h>
  12 #include <asm/errno.h>
  13 #include <dm/device.h>
  14 #include <serial.h>
  15 #include <fdtdec.h>
  16
  17 /*
  18  * Note: Register map is slightly different from that of 16550.
  19  */
  20 struct uniphier_serial {
  21         u32 rx;                 /* In:  Receive buffer */
  22 #define tx rx                   /* Out: Transmit buffer */
  23         u32 ier;                /* Interrupt Enable Register */
  24         u32 iir;                /* In: Interrupt ID Register */
  25         u32 char_fcr;           /* Charactor / FIFO Control Register */
  26         u32 lcr_mcr;            /* Line/Modem Control Register */
  27 #define LCR_SHIFT       8
  28 #define LCR_MASK        (0xff << (LCR_SHIFT))
  29         u32 lsr;                /* In: Line Status Register */
  30         u32 msr;                /* In: Modem Status Register */
  31         u32 __rsv0;
  32         u32 __rsv1;
  33         u32 dlr;                /* Divisor Latch Register */
  34 };
  35
  36 struct uniphier_serial_private_data {
  37         struct uniphier_serial __iomem *membase;
  38         unsigned int uartclk;
  39 };
  40
  41 #define uniphier_serial_port(dev)       \
  42         ((struct uniphier_serial_private_data *)dev_get_priv(dev))->membase
  43
  44 static int uniphier_serial_setbrg(struct udevice *dev, int baudrate)
  45 {
  46         struct uniphier_serial_private_data *priv = dev_get_priv(dev);
  47         struct uniphier_serial __iomem *port = uniphier_serial_port(dev);
  48         const unsigned int mode_x_div = 16;
  49         unsigned int divisor;
  50
  51         divisor = DIV_ROUND_CLOSEST(priv->uartclk, mode_x_div * baudrate);
  52
  53         writel(divisor, &port->dlr);
  54
  55         return 0;
  56 }
  57
  58 static int uniphier_serial_getc(struct udevice *dev)
  59 {
  60         struct uniphier_serial __iomem *port = uniphier_serial_port(dev);
  61
  62         if (!(readl(&port->lsr) & UART_LSR_DR))
  63                 return -EAGAIN;
  64
  65         return readl(&port->rx);
  66 }
  67
  68 static int uniphier_serial_putc(struct udevice *dev, const char c)
  69 {
  70         struct uniphier_serial __iomem *port = uniphier_serial_port(dev);
  71
  72         if (!(readl(&port->lsr) & UART_LSR_THRE))
  73                 return -EAGAIN;
  74
  75         writel(c, &port->tx);
  76
  77         return 0;
  78 }
  79
  80 static int uniphier_serial_pending(struct udevice *dev, bool input)
  81 {
  82         struct uniphier_serial __iomem *port = uniphier_serial_port(dev);
  83
  84         if (input)
  85                 return readl(&port->lsr) & UART_LSR_DR;
  86         else
  87                 return !(readl(&port->lsr) & UART_LSR_THRE);
  88 }
  89
  90 static int uniphier_serial_probe(struct udevice *dev)
  91 {
  92         DECLARE_GLOBAL_DATA_PTR;
  93         struct uniphier_serial_private_data *priv = dev_get_priv(dev);
  94         struct uniphier_serial __iomem *port;
  95         fdt_addr_t base;
  96         u32 tmp;
  97
  98         base = dev_get_addr(dev);
  99         if (base == FDT_ADDR_T_NONE)
 100                 return -EINVAL;
 101
 102         port = devm_ioremap(dev, base, SZ_64);
 103         if (!port)
 104                 return -ENOMEM;
 105
 106         priv->membase = port;
 107
 108         priv->uartclk = fdtdec_get_int(gd->fdt_blob, dev->of_offset,
 109                                        "clock-frequency", 0);
 110
 111         tmp = readl(&port->lcr_mcr);
 112         tmp &= ~LCR_MASK;
 113         tmp |= UART_LCR_WLEN8 << LCR_SHIFT;
 114         writel(tmp, &port->lcr_mcr);
 115
 116         return 0;
 117 }
 118
 119 static const struct udevice_id uniphier_uart_of_match[] = {
 120         { .compatible = "socionext,uniphier-uart" },
 121         { /* sentinel */ }
 122 };
 123
 124 static const struct dm_serial_ops uniphier_serial_ops = {
 125         .setbrg = uniphier_serial_setbrg,
 126         .getc = uniphier_serial_getc,
 127         .putc = uniphier_serial_putc,
 128         .pending = uniphier_serial_pending,
 129 };
 130
 131 U_BOOT_DRIVER(uniphier_serial) = {
 132         .name = "uniphier-uart",
 133         .id = UCLASS_SERIAL,
 134         .of_match = uniphier_uart_of_match,
 135         .probe = uniphier_serial_probe,
 136         .priv_auto_alloc_size = sizeof(struct uniphier_serial_private_data),
 137         .ops = &uniphier_serial_ops,
 138 };