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 <common.h>
  10 #include <dm.h>
  11 #include <linux/io.h>
  12 #include <linux/serial_reg.h>
  13 #include <linux/sizes.h>
  14 #include <linux/errno.h>
  15 #include <serial.h>
  16 #include <fdtdec.h>
  17
  18 /*
  19  * Note: Register map is slightly different from that of 16550.
  20  */
  21 struct uniphier_serial {
  22         u32 rx;                 /* In:  Receive buffer */
  23 #define tx rx                   /* Out: Transmit buffer */
  24         u32 ier;                /* Interrupt Enable Register */
  25         u32 iir;                /* In: Interrupt ID Register */
  26         u32 char_fcr;           /* Charactor / FIFO Control Register */
  27         u32 lcr_mcr;            /* Line/Modem Control Register */
  28 #define LCR_SHIFT       8
  29 #define LCR_MASK        (0xff << (LCR_SHIFT))
  30         u32 lsr;                /* In: Line Status Register */
  31         u32 msr;                /* In: Modem Status Register */
  32         u32 __rsv0;
  33         u32 __rsv1;
  34         u32 dlr;                /* Divisor Latch Register */
  35 };
  36
  37 struct uniphier_serial_private_data {
  38         struct uniphier_serial __iomem *membase;
  39         unsigned int uartclk;
  40 };
  41
  42 #define uniphier_serial_port(dev)       \
  43         ((struct uniphier_serial_private_data *)dev_get_priv(dev))->membase
  44
  45 static int uniphier_serial_setbrg(struct udevice *dev, int baudrate)
  46 {
  47         struct uniphier_serial_private_data *priv = dev_get_priv(dev);
  48         struct uniphier_serial __iomem *port = uniphier_serial_port(dev);
  49         const unsigned int mode_x_div = 16;
  50         unsigned int divisor;
  51
  52         divisor = DIV_ROUND_CLOSEST(priv->uartclk, mode_x_div * baudrate);
  53
  54         writel(divisor, &port->dlr);
  55
  56         return 0;
  57 }
  58
  59 static int uniphier_serial_getc(struct udevice *dev)
  60 {
  61         struct uniphier_serial __iomem *port = uniphier_serial_port(dev);
  62
  63         if (!(readl(&port->lsr) & UART_LSR_DR))
  64                 return -EAGAIN;
  65
  66         return readl(&port->rx);
  67 }
  68
  69 static int uniphier_serial_putc(struct udevice *dev, const char c)
  70 {
  71         struct uniphier_serial __iomem *port = uniphier_serial_port(dev);
  72
  73         if (!(readl(&port->lsr) & UART_LSR_THRE))
  74                 return -EAGAIN;
  75
  76         writel(c, &port->tx);
  77
  78         return 0;
  79 }
  80
  81 static int uniphier_serial_pending(struct udevice *dev, bool input)
  82 {
  83         struct uniphier_serial __iomem *port = uniphier_serial_port(dev);
  84
  85         if (input)
  86                 return readl(&port->lsr) & UART_LSR_DR;
  87         else
  88                 return !(readl(&port->lsr) & UART_LSR_THRE);
  89 }
  90
  91 static int uniphier_serial_probe(struct udevice *dev)
  92 {
  93         DECLARE_GLOBAL_DATA_PTR;
  94         struct uniphier_serial_private_data *priv = dev_get_priv(dev);
  95         struct uniphier_serial __iomem *port;
  96         fdt_addr_t base;
  97         u32 tmp;
  98
  99         base = devfdt_get_addr(dev);
 100         if (base == FDT_ADDR_T_NONE)
 101                 return -EINVAL;
 102
 103         port = devm_ioremap(dev, base, SZ_64);
 104         if (!port)
 105                 return -ENOMEM;
 106
 107         priv->membase = port;
 108
 109         priv->uartclk = fdtdec_get_int(gd->fdt_blob, dev_of_offset(dev),
 110                                        "clock-frequency", 0);
 111
 112         tmp = readl(&port->lcr_mcr);
 113         tmp &= ~LCR_MASK;
 114         tmp |= UART_LCR_WLEN8 << LCR_SHIFT;
 115         writel(tmp, &port->lcr_mcr);
 116
 117         return 0;
 118 }
 119
 120 static const struct udevice_id uniphier_uart_of_match[] = {
 121         { .compatible = "socionext,uniphier-uart" },
 122         { /* sentinel */ }
 123 };
 124
 125 static const struct dm_serial_ops uniphier_serial_ops = {
 126         .setbrg = uniphier_serial_setbrg,
 127         .getc = uniphier_serial_getc,
 128         .putc = uniphier_serial_putc,
 129         .pending = uniphier_serial_pending,
 130 };
 131
 132 U_BOOT_DRIVER(uniphier_serial) = {
 133         .name = "uniphier-uart",
 134         .id = UCLASS_SERIAL,
 135         .of_match = uniphier_uart_of_match,
 136         .probe = uniphier_serial_probe,
 137         .priv_auto_alloc_size = sizeof(struct uniphier_serial_private_data),
 138         .ops = &uniphier_serial_ops,
 139 };