Patchwork [v8,3/8] ARM: exynos4210: UART support

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Submitter Evgeny Voevodin
Date Jan. 19, 2012, 8:31 a.m.
Message ID <1326961896-25420-4-git-send-email-e.voevodin@samsung.com>
Download mbox | patch
Permalink /patch/136791/
State New
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Comments

Evgeny Voevodin - Jan. 19, 2012, 8:31 a.m.
From: Maksim Kozlov <m.kozlov@samsung.com>

Add basic support of exynos4210 UART

Signed-off-by: Evgeny Voevodin <e.voevodin@samsung.com>
---
 Makefile.target      |    2 +-
 hw/exynos4210.c      |   29 +++
 hw/exynos4210.h      |    9 +
 hw/exynos4210_uart.c |  668 ++++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 707 insertions(+), 1 deletions(-)
 create mode 100644 hw/exynos4210_uart.c
Peter Maydell - Jan. 19, 2012, 12:35 p.m.
On 19 January 2012 08:31, Evgeny Voevodin <e.voevodin@samsung.com> wrote:
> From: Maksim Kozlov <m.kozlov@samsung.com>
> +static Exynos4210UartReg exynos4210_uart_regs[] = {
> +        {"ULCON"   , ULCON   , 0x00000000},
> +        {"UCON"    , UCON    , 0x00003000},
> +        {"UFCON"   , UFCON   , 0x00000000},
> +        {"UMCON"   , UMCON   , 0x00000000},
> +        {"UTRSTAT" , UTRSTAT , 0x00000006}, /* RO */
> +        {"UERSTAT" , UERSTAT , 0x00000000}, /* RO */
> +        {"UFSTAT"  , UFSTAT  , 0x00000000}, /* RO */
> +        {"UMSTAT"  , UMSTAT  , 0x00000000}, /* RO */
> +        {"UTXH"    , UTXH    , 0x5c5c5c5c}, /* WO, undefined reset value*/
> +        {"URXH"    , URXH    , 0x00000000}, /* RO */
> +        {"UBRDIV"  , UBRDIV  , 0x00000000},
> +        {"UFRACVAL", UFRACVAL, 0x00000000},
> +        {"UINTP"   , UINTP   , 0x00000000},
> +        {"UINTSP"  , UINTSP  , 0x00000000},
> +        {"UINTM"   , UINTM   , 0x00000000},
> +};

Indentation again.

> +static void exynos4210_uart_event(void *opaque, int event)
> +{
> +    /*
> +     * TODO: Implement this.
> +     *
> +     */
> +}

Implement this :-) You only need to handle CHR_EVENT_BREAK, so
it shouldn't be very hard.

-- PMM

Patch

diff --git a/Makefile.target b/Makefile.target
index 6199d44..c856de3 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -340,7 +340,7 @@  obj-arm-y += arm_boot.o pl011.o pl031.o pl050.o pl080.o pl110.o pl181.o pl190.o
 obj-arm-y += versatile_pci.o
 obj-arm-y += realview_gic.o realview.o arm_sysctl.o arm11mpcore.o a9mpcore.o
 obj-arm-y += exynos4210_gic.o exynos4210_combiner.o exynos4210.o
-obj-arm-y += exynos4_boards.o
+obj-arm-y += exynos4_boards.o exynos4210_uart.o
 obj-arm-y += arm_l2x0.o
 obj-arm-y += arm_mptimer.o
 obj-arm-y += armv7m.o armv7m_nvic.o stellaris.o pl022.o stellaris_enet.o
diff --git a/hw/exynos4210.c b/hw/exynos4210.c
index 82755db..f23a136 100644
--- a/hw/exynos4210.c
+++ b/hw/exynos4210.c
@@ -29,6 +29,18 @@ 
 
 #define EXYNOS4210_CHIPID_ADDR         0x10000000
 
+/* UART's definitions */
+#define EXYNOS4210_UART0_BASE_ADDR     0x13800000
+#define EXYNOS4210_UART1_BASE_ADDR     0x13810000
+#define EXYNOS4210_UART2_BASE_ADDR     0x13820000
+#define EXYNOS4210_UART3_BASE_ADDR     0x13830000
+#define EXYNOS4210_UART0_FIFO_SIZE     256
+#define EXYNOS4210_UART1_FIFO_SIZE     64
+#define EXYNOS4210_UART2_FIFO_SIZE     16
+#define EXYNOS4210_UART3_FIFO_SIZE     16
+/* Interrupt Group of External Interrupt Combiner for UART */
+#define EXYNOS4210_UART_INT_GRP        26
+
 /* External GIC */
 #define EXYNOS4210_EXT_GIC_CPU_BASE_ADDR    0x10480000
 #define EXYNOS4210_EXT_GIC_DIST_BASE_ADDR   0x10490000
@@ -198,5 +210,22 @@  Exynos4210State *exynos4210_init(MemoryRegion *system_mem,
     memory_region_add_subregion(system_mem, EXYNOS4210_SECOND_CPU_BOOTREG,
             &s->bootreg_mem);
 
+    /*** UARTs ***/
+    exynos4210_uart_create(EXYNOS4210_UART0_BASE_ADDR,
+                           EXYNOS4210_UART0_FIFO_SIZE, 0, NULL,
+                    irq_table[exynos4210_get_irq(EXYNOS4210_UART_INT_GRP, 0)]);
+
+    exynos4210_uart_create(EXYNOS4210_UART1_BASE_ADDR,
+                           EXYNOS4210_UART1_FIFO_SIZE, 1, NULL,
+                    irq_table[exynos4210_get_irq(EXYNOS4210_UART_INT_GRP, 1)]);
+
+    exynos4210_uart_create(EXYNOS4210_UART2_BASE_ADDR,
+                           EXYNOS4210_UART2_FIFO_SIZE, 2, NULL,
+                    irq_table[exynos4210_get_irq(EXYNOS4210_UART_INT_GRP, 2)]);
+
+    exynos4210_uart_create(EXYNOS4210_UART3_BASE_ADDR,
+                           EXYNOS4210_UART3_FIFO_SIZE, 3, NULL,
+                    irq_table[exynos4210_get_irq(EXYNOS4210_UART_INT_GRP, 3)]);
+
     return s;
 }
diff --git a/hw/exynos4210.h b/hw/exynos4210.h
index a68900d..008b94f 100644
--- a/hw/exynos4210.h
+++ b/hw/exynos4210.h
@@ -116,4 +116,13 @@  uint32_t exynos4210_get_irq(uint32_t grp, uint32_t bit);
 void exynos4210_combiner_get_gpioin(Exynos4210Irq *irqs, DeviceState *dev,
         int ext);
 
+/*
+ * exynos4210 UART
+ */
+DeviceState *exynos4210_uart_create(target_phys_addr_t addr,
+                                    int fifo_size,
+                                    int channel,
+                                    CharDriverState *chr,
+                                    qemu_irq irq);
+
 #endif /* EXYNOS4210_H_ */
diff --git a/hw/exynos4210_uart.c b/hw/exynos4210_uart.c
new file mode 100644
index 0000000..050121f
--- /dev/null
+++ b/hw/exynos4210_uart.c
@@ -0,0 +1,668 @@ 
+/*
+ *  exynos4210 UART Emulation
+ *
+ *  Copyright (C) 2011 Samsung Electronics Co Ltd.
+ *    Maksim Kozlov, <m.kozlov@samsung.com>
+ *
+ *  Created on: 07.2011
+ *
+ *
+ *  This program is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License as published by the
+ *  Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ *  for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "sysbus.h"
+#include "sysemu.h"
+#include "qemu-char.h"
+
+#include "exynos4210.h"
+
+#undef DEBUG_UART
+#undef DEBUG_UART_EXTEND
+#undef DEBUG_IRQ
+#undef DEBUG_Rx_DATA
+#undef DEBUG_Tx_DATA
+
+
+//#define DEBUG_UART
+//#define DEBUG_UART_EXTEND
+//#define DEBUG_IRQ
+//#define DEBUG_Rx_DATA
+//#define DEBUG_Tx_DATA
+
+
+#define  PRINT_DEBUG(fmt, args...)  \
+        do {} while (0)
+#define  PRINT_DEBUG_EXTEND(fmt, args...) \
+        do {} while (0)
+#define  PRINT_ERROR(fmt, args...) \
+        do { \
+            fprintf(stderr, "  [%s:%d]   "fmt, __func__, __LINE__, ##args); \
+        } while (0)
+
+#ifdef DEBUG_UART
+
+#undef PRINT_DEBUG
+#define  PRINT_DEBUG(fmt, args...)  \
+        do { \
+            fprintf(stderr, "  [%s:%d]   "fmt, __func__, __LINE__, ##args); \
+        } while (0)
+
+#ifdef DEBUG_UART_EXTEND
+
+#undef PRINT_DEBUG_EXTEND
+#define  PRINT_DEBUG_EXTEND(fmt, args...) \
+        do { \
+            fprintf(stderr, "  [%s:%d]   "fmt, __func__, __LINE__, ##args); \
+        } while (0)
+
+#endif /* EXTEND */
+#endif
+
+
+/*
+ *  Offsets for UART registers relative to SFR base address
+ *  for UARTn
+ *
+ */
+#define ULCON      0x0000 /* Line Control             */
+#define UCON       0x0004 /* Control                  */
+#define UFCON      0x0008 /* FIFO Control             */
+#define UMCON      0x000C /* Modem Control            */
+#define UTRSTAT    0x0010 /* Tx/Rx Status             */
+#define UERSTAT    0x0014 /* Rx Error Status          */
+#define UFSTAT     0x0018 /* FIFO Status              */
+#define UMSTAT     0x001C /* Modem Status             */
+#define UTXH       0x0020 /* Transmit Buffer          */
+#define URXH       0x0024 /* Receive Buffer           */
+#define UBRDIV     0x0028 /* Baud Rate Divisor        */
+#define UFRACVAL   0x002C /* Divisor Fractional Value */
+#define UINTP      0x0030 /* Interrupt Pending        */
+#define UINTSP     0x0034 /* Interrupt Source Pending */
+#define UINTM      0x0038 /* Interrupt Mask           */
+
+/*
+ * for indexing register in the uint32_t array
+ *
+ * 'reg' - register offset (see offsets definitions above)
+ *
+ */
+#define I_(reg) (reg / sizeof(uint32_t))
+
+typedef struct Exynos4210UartReg {
+    const char         *name; /* the only reason is the debug output */
+    target_phys_addr_t  offset;
+    uint32_t            reset_value;
+} Exynos4210UartReg;
+
+static Exynos4210UartReg exynos4210_uart_regs[] = {
+        {"ULCON"   , ULCON   , 0x00000000},
+        {"UCON"    , UCON    , 0x00003000},
+        {"UFCON"   , UFCON   , 0x00000000},
+        {"UMCON"   , UMCON   , 0x00000000},
+        {"UTRSTAT" , UTRSTAT , 0x00000006}, /* RO */
+        {"UERSTAT" , UERSTAT , 0x00000000}, /* RO */
+        {"UFSTAT"  , UFSTAT  , 0x00000000}, /* RO */
+        {"UMSTAT"  , UMSTAT  , 0x00000000}, /* RO */
+        {"UTXH"    , UTXH    , 0x5c5c5c5c}, /* WO, undefined reset value*/
+        {"URXH"    , URXH    , 0x00000000}, /* RO */
+        {"UBRDIV"  , UBRDIV  , 0x00000000},
+        {"UFRACVAL", UFRACVAL, 0x00000000},
+        {"UINTP"   , UINTP   , 0x00000000},
+        {"UINTSP"  , UINTSP  , 0x00000000},
+        {"UINTM"   , UINTM   , 0x00000000},
+};
+
+#define EXYNOS4210_UART_REGS_MEM_SIZE    0x3c
+
+/* UART FIFO Control */
+#define UFCON_FIFO_ENABLE                    0x1
+#define UFCON_Rx_FIFO_RESET                  0x2
+#define UFCON_Tx_FIFO_RESET                  0x4
+#define UFCON_Tx_FIFO_TRIGGER_LEVEL_SHIFT    8
+#define UFCON_Tx_FIFO_TRIGGER_LEVEL \
+        (7 << UFCON_Tx_FIFO_TRIGGER_LEVEL_SHIFT)
+#define UFCON_Rx_FIFO_TRIGGER_LEVEL_SHIFT    4
+#define UFCON_Rx_FIFO_TRIGGER_LEVEL \
+        (7 << UFCON_Rx_FIFO_TRIGGER_LEVEL_SHIFT)
+
+/* Uart FIFO Status */
+#define UFSTAT_Rx_FIFO_COUNT        0xff
+#define UFSTAT_Rx_FIFO_FULL         0x100
+#define UFSTAT_Rx_FIFO_ERROR        0x200
+#define UFSTAT_Tx_FIFO_COUNT_SHIFT  16
+#define UFSTAT_Tx_FIFO_COUNT        (0xff << UFSTAT_Tx_FIFO_COUNT_SHIFT)
+#define UFSTAT_Tx_FIFO_FULL_SHIFT   24
+#define UFSTAT_Tx_FIFO_FULL         (1 << UFSTAT_Tx_FIFO_FULL_SHIFT)
+
+/* UART Interrupt Source Pending */
+#define UINTSP_RXD      0x1 /* Receive interrupt  */
+#define UINTSP_ERROR    0x2 /* Error interrupt    */
+#define UINTSP_TXD      0x4 /* Transmit interrupt */
+#define UINTSP_MODEM    0x8 /* Modem interrupt    */
+
+/* UART Line Control */
+#define ULCON_IR_MODE_SHIFT   6
+#define ULCON_PARITY_SHIFT    3
+#define ULCON_STOP_BIT_SHIFT  1
+
+
+
+/* Specifies Tx/Rx Status */
+#define UTRSTAT_TRANSMITTER_EMPTY       0x4
+#define UTRSTAT_Tx_BUFFER_EMPTY         0x2
+#define UTRSTAT_Rx_BUFFER_DATA_READY    0x1
+
+typedef struct {
+    uint8_t    *data;
+    uint32_t    sp, rp; /* store and retrieve pointers */
+    uint32_t    size;
+} Exynos4210UartFIFO;
+
+typedef struct {
+    SysBusDevice busdev;
+    MemoryRegion iomem;
+
+    uint32_t             reg[EXYNOS4210_UART_REGS_MEM_SIZE];
+    Exynos4210UartFIFO   rx;
+    Exynos4210UartFIFO   tx;
+
+    CharDriverState  *chr;
+    qemu_irq          irq;
+
+    uint32_t channel;
+
+} Exynos4210UartState;
+
+
+#ifdef DEBUG_UART
+/* The only meaning of life - debugging. This functions should be only used
+ * inside PRINT_DEBUG_... macros
+ */
+static const char *exynos4210_uart_regname(target_phys_addr_t  offset)
+{
+
+    int regs_number = sizeof(exynos4210_uart_regs) / sizeof(Exynos4210UartReg);
+    int i;
+
+    for (i = 0; i < regs_number; i++) {
+        if (offset == exynos4210_uart_regs[i].offset) {
+            return exynos4210_uart_regs[i].name;
+        }
+    }
+
+    return NULL;
+}
+#endif
+
+
+static void fifo_store(Exynos4210UartFIFO *q, uint8_t ch)
+{
+    q->data[q->sp] = ch;
+    q->sp = (q->sp + 1) % q->size;
+}
+
+static uint8_t fifo_retrieve(Exynos4210UartFIFO *q)
+{
+    uint8_t ret = q->data[q->rp];
+    q->rp = (q->rp + 1) % q->size;
+    return  ret;
+}
+
+static int fifo_elements_number(Exynos4210UartFIFO *q)
+{
+    if (q->sp < q->rp) {
+        return q->size - q->rp + q->sp;
+    }
+
+    return q->sp - q->rp;
+}
+
+static int fifo_empty_elements_number(Exynos4210UartFIFO *q)
+{
+    return q->size - fifo_elements_number(q);
+}
+
+static void fifo_reset(Exynos4210UartFIFO *q)
+{
+    if (q->data != NULL) {
+        g_free(q->data);
+        q->data = NULL;
+    }
+
+    q->data = (uint8_t *)g_malloc0(q->size);
+
+    q->sp = 0;
+    q->rp = 0;
+}
+
+static uint32_t exynos4210_uart_Tx_FIFO_trigger_level(Exynos4210UartState *s)
+{
+    uint32_t level = 0;
+    uint32_t reg;
+
+    reg = (s->reg[I_(UFCON)] && UFCON_Tx_FIFO_TRIGGER_LEVEL) >>
+            UFCON_Tx_FIFO_TRIGGER_LEVEL_SHIFT;
+
+    switch (s->channel) {
+    case 0:
+        level = reg * 32;
+        break;
+    case 1:
+    case 4:
+        level = reg * 8;
+        break;
+    case 2:
+    case 3:
+        level = reg * 2;
+        break;
+    default:
+        level = 0;
+        PRINT_ERROR("Wrong UART channel number: %d\n", s->channel);
+    }
+
+    return level;
+}
+
+static void exynos4210_uart_update_irq(Exynos4210UartState *s)
+{
+    /*
+     * The Tx interrupt is always requested if the number of data in the
+     * transmit FIFO is smaller than the trigger level.
+     */
+    if (s->reg[I_(UFCON)] && UFCON_FIFO_ENABLE) {
+
+        uint32_t count = (s->reg[I_(UFSTAT)] && UFSTAT_Tx_FIFO_COUNT) >>
+                UFSTAT_Tx_FIFO_COUNT_SHIFT;
+
+        if (count <= exynos4210_uart_Tx_FIFO_trigger_level(s)) {
+            s->reg[I_(UINTSP)] |= UINTSP_TXD;
+        }
+    }
+
+    s->reg[I_(UINTP)] = s->reg[I_(UINTSP)] & ~s->reg[I_(UINTM)];
+
+    if (s->reg[I_(UINTP)]) {
+        qemu_irq_raise(s->irq);
+
+#ifdef DEBUG_IRQ
+        fprintf(stderr, "UART%d: IRQ has been raised: %08x\n",
+                s->channel, s->reg[I_(UINTP)]);
+#endif
+
+    } else {
+        qemu_irq_lower(s->irq);
+    }
+}
+
+static void exynos4210_uart_update_parameters(Exynos4210UartState *s)
+{
+    int speed, parity, data_bits, stop_bits, frame_size;
+    QEMUSerialSetParams ssp;
+    uint64_t uclk_rate;
+
+    if (s->reg[I_(UBRDIV)] == 0) {
+        return;
+    }
+
+    frame_size = 1; /* start bit */
+    if (s->reg[I_(ULCON)] & 0x20) {
+        frame_size++; /* parity bit */
+        if (s->reg[I_(ULCON)] & 0x28) {
+            parity = 'E';
+        } else {
+            parity = 'O';
+        }
+    } else {
+        parity = 'N';
+    }
+
+    if (s->reg[I_(ULCON)] & 0x4) {
+        stop_bits = 2;
+    } else {
+        stop_bits = 1;
+    }
+
+    data_bits = (s->reg[I_(ULCON)] & 0x3) + 5;
+
+    frame_size += data_bits + stop_bits;
+
+    uclk_rate = 24000000;
+
+    speed = uclk_rate / ((16 * (s->reg[I_(UBRDIV)]) & 0xffff) +
+            (s->reg[I_(UFRACVAL)] & 0x7) + 16);
+
+    ssp.speed     = speed;
+    ssp.parity    = parity;
+    ssp.data_bits = data_bits;
+    ssp.stop_bits = stop_bits;
+
+    qemu_chr_fe_ioctl(s->chr, CHR_IOCTL_SERIAL_SET_PARAMS, &ssp);
+
+    PRINT_DEBUG("UART%d: speed: %d, parity: %c, data: %d, stop: %d\n",
+                s->channel, speed, parity, data_bits, stop_bits);
+}
+
+static void exynos4210_uart_write(void *opaque, target_phys_addr_t offset,
+                               uint64_t val, unsigned size)
+{
+    Exynos4210UartState *s = (Exynos4210UartState *)opaque;
+    uint8_t ch;
+
+    if (offset > (EXYNOS4210_UART_REGS_MEM_SIZE - sizeof(uint32_t))) {
+        hw_error("exynos4210_cmu_write: Bad offset 0x%x\n", (int)offset);
+    }
+
+    PRINT_DEBUG_EXTEND("UART%d: <0x%04x> %s <- 0x%08llx\n",
+                   s->channel, offset, exynos4210_uart_regname(offset), val);
+
+    switch (offset) {
+    case ULCON:
+    case UBRDIV:
+    case UFRACVAL:
+        s->reg[I_(offset)] = val;
+        exynos4210_uart_update_parameters(s);
+        break;
+    case UFCON:
+        s->reg[I_(UFCON)] = val;
+        if (val & UFCON_Rx_FIFO_RESET) {
+            fifo_reset(&s->rx);
+            s->reg[I_(UFCON)] &= ~UFCON_Rx_FIFO_RESET;
+            PRINT_DEBUG("UART%d: Rx FIFO Reset\n", s->channel);
+        }
+        if (val & UFCON_Tx_FIFO_RESET) {
+            fifo_reset(&s->tx);
+            s->reg[I_(UFCON)] &= ~UFCON_Tx_FIFO_RESET;
+            PRINT_DEBUG("UART%d: Tx FIFO Reset\n", s->channel);
+        }
+        break;
+
+    case UTXH:
+        if (s->chr) {
+            s->reg[I_(UTRSTAT)] &= ~(UTRSTAT_TRANSMITTER_EMPTY |
+                    UTRSTAT_Tx_BUFFER_EMPTY);
+            ch = (uint8_t)val;
+            qemu_chr_fe_write(s->chr, &ch, 1);
+#ifdef DEBUG_Tx_DATA
+            fprintf(stderr, "%c", ch);
+#endif
+            s->reg[I_(UTRSTAT)] |= UTRSTAT_TRANSMITTER_EMPTY |
+                    UTRSTAT_Tx_BUFFER_EMPTY;
+            s->reg[I_(UINTSP)]  |= UINTSP_TXD;
+            exynos4210_uart_update_irq(s);
+        }
+        break;
+
+    case UINTP:
+        s->reg[I_(UINTP)] &= ~val;
+        s->reg[I_(UINTSP)] &= ~val;
+        PRINT_DEBUG("UART%d: UINTP [%04x] have been cleared: %08x\n",
+                    s->channel, offset, s->reg[I_(UINTP)]);
+        exynos4210_uart_update_irq(s);
+        break;
+    case UTRSTAT:
+    case UERSTAT:
+    case UFSTAT:
+    case UMSTAT:
+    case URXH:
+        PRINT_DEBUG("UART%d: Trying to write into RO register: %s [%04x]\n",
+                    s->channel, exynos4210_uart_regname(offset), offset);
+        break;
+    case UINTSP:
+        s->reg[I_(UINTSP)]  &= ~val;
+        break;
+    case UINTM:
+        s->reg[I_(UINTM)] = val;
+        exynos4210_uart_update_irq(s);
+        break;
+    case UCON:
+    case UMCON:
+    default:
+        s->reg[I_(offset)] = val;
+        break;
+    }
+}
+static uint64_t exynos4210_uart_read(void *opaque, target_phys_addr_t offset,
+                                  unsigned size)
+{
+    Exynos4210UartState *s = (Exynos4210UartState *)opaque;
+    uint32_t res;
+
+    if (offset > (EXYNOS4210_UART_REGS_MEM_SIZE - sizeof(uint32_t))) {
+        hw_error("exynos4210_cmu_read: Bad offset 0x%x\n", (int)offset);
+    }
+
+    switch (offset) {
+    case UERSTAT: /* Read Only */
+        res = s->reg[I_(UERSTAT)];
+        s->reg[I_(UERSTAT)] = 0;
+        return res;
+    case UFSTAT: /* Read Only */
+        s->reg[I_(UFSTAT)] = fifo_elements_number(&s->rx) & 0xff;
+        if (fifo_empty_elements_number(&s->rx) == 0) {
+            s->reg[I_(UFSTAT)] |= UFSTAT_Rx_FIFO_FULL;
+            s->reg[I_(UFSTAT)] &= ~0xff;
+        }
+        return s->reg[I_(UFSTAT)];
+    case URXH:
+        if (s->reg[I_(UFCON)] & UFCON_FIFO_ENABLE) {
+            if (fifo_elements_number(&s->rx)) {
+                res = fifo_retrieve(&s->rx);
+#ifdef DEBUG_Rx_DATA
+                fprintf(stderr, "%c", res);
+#endif
+                if (!fifo_elements_number(&s->rx)) {
+                    s->reg[I_(UTRSTAT)] &= ~UTRSTAT_Rx_BUFFER_DATA_READY;
+                } else {
+                    s->reg[I_(UTRSTAT)] |= UTRSTAT_Rx_BUFFER_DATA_READY;
+                }
+            } else {
+                s->reg[I_(UINTSP)] |= UINTSP_ERROR;
+                exynos4210_uart_update_irq(s);
+                res = 0;
+            }
+        } else {
+            s->reg[I_(UTRSTAT)] &= ~UTRSTAT_Rx_BUFFER_DATA_READY;
+            res = s->reg[I_(URXH)];
+        }
+        return res;
+    case UTXH:
+        PRINT_DEBUG("UART%d: Trying to read from WO register: %s [%04x]\n",
+                    s->channel, exynos4210_uart_regname(offset), offset);
+        break;
+    default:
+        return s->reg[I_(offset)];
+        break;
+    }
+
+    return 0;
+}
+
+
+static const MemoryRegionOps exynos4210_uart_ops = {
+    .read = exynos4210_uart_read,
+    .write = exynos4210_uart_write,
+    .endianness = DEVICE_NATIVE_ENDIAN,
+};
+
+static int exynos4210_uart_can_receive(void *opaque)
+{
+    Exynos4210UartState *s = (Exynos4210UartState *)opaque;
+
+    return fifo_empty_elements_number(&s->rx);
+}
+
+
+static void exynos4210_uart_receive(void *opaque, const uint8_t *buf, int size)
+{
+    Exynos4210UartState *s = (Exynos4210UartState *)opaque;
+    int i;
+
+    if (s->reg[I_(UFCON)] & UFCON_FIFO_ENABLE) {
+        if (fifo_empty_elements_number(&s->rx) < size) {
+            for (i = 0; i < fifo_empty_elements_number(&s->rx); i++) {
+                fifo_store(&s->rx, buf[i]);
+            }
+            s->reg[I_(UINTSP)] |= UINTSP_ERROR;
+            s->reg[I_(UTRSTAT)] |= UTRSTAT_Rx_BUFFER_DATA_READY;
+        } else {
+            for (i = 0; i < size; i++) {
+                fifo_store(&s->rx, buf[i]);
+            }
+            s->reg[I_(UTRSTAT)] |= UTRSTAT_Rx_BUFFER_DATA_READY;
+        }
+        /* XXX: Around here we maybe should check Rx trigger level */
+        s->reg[I_(UINTSP)] |= UINTSP_RXD;
+    } else {
+        s->reg[I_(URXH)] = buf[0];
+        s->reg[I_(UINTSP)] |= UINTSP_RXD;
+        s->reg[I_(UTRSTAT)] |= UTRSTAT_Rx_BUFFER_DATA_READY;
+    }
+
+    exynos4210_uart_update_irq(s);
+}
+
+
+static void exynos4210_uart_event(void *opaque, int event)
+{
+    /*
+     * TODO: Implement this.
+     *
+     */
+}
+
+
+static void exynos4210_uart_reset(DeviceState *dev)
+{
+    Exynos4210UartState *s =
+            container_of(dev, Exynos4210UartState, busdev.qdev);
+    int regs_number = sizeof(exynos4210_uart_regs)/sizeof(Exynos4210UartReg);
+    int i;
+
+    for (i = 0; i < regs_number; i++) {
+        s->reg[I_(exynos4210_uart_regs[i].offset)] =
+                exynos4210_uart_regs[i].reset_value;
+    }
+
+    fifo_reset(&s->rx);
+    fifo_reset(&s->tx);
+
+    PRINT_DEBUG("UART%d: Rx FIFO size: %d\n", s->channel, s->rx.size);
+}
+
+static const VMStateDescription vmstate_exynos4210_uart_fifo = {
+    .name = "exynos4210.uart.fifo",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .minimum_version_id_old = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT32(sp, Exynos4210UartFIFO),
+        VMSTATE_UINT32(rp, Exynos4210UartFIFO),
+        VMSTATE_VBUFFER_UINT32(data, Exynos4210UartFIFO, 1, NULL, 0, size),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static const VMStateDescription vmstate_exynos4210_uart = {
+    .name = "exynos4210.uart",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .minimum_version_id_old = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_STRUCT(rx, Exynos4210UartState, 1,
+                       vmstate_exynos4210_uart_fifo, Exynos4210UartFIFO),
+        VMSTATE_UINT32_ARRAY(reg, Exynos4210UartState,
+                             EXYNOS4210_UART_REGS_MEM_SIZE),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+DeviceState *exynos4210_uart_create(target_phys_addr_t addr,
+                                 int fifo_size,
+                                 int channel,
+                                 CharDriverState *chr,
+                                 qemu_irq irq)
+{
+    DeviceState  *dev;
+    SysBusDevice *bus;
+
+    dev = qdev_create(NULL, "exynos4210.uart");
+
+    if (!chr) {
+        if (channel >= MAX_SERIAL_PORTS) {
+            hw_error("Only %d serial ports are supported by QEMU.\n",
+                     MAX_SERIAL_PORTS);
+        }
+        chr = serial_hds[channel];
+        if (!chr) {
+            chr = qemu_chr_new("exynos4210.uart", "null", NULL);
+            if (!(chr)) {
+                hw_error("Can't assign serial port to UART%d.\n", channel);
+            }
+        }
+    }
+
+    qdev_prop_set_chr(dev, "chardev", chr);
+    qdev_prop_set_uint32(dev, "channel", channel);
+    qdev_prop_set_uint32(dev, "rx-size", fifo_size);
+    qdev_prop_set_uint32(dev, "tx-size", fifo_size);
+
+    bus = sysbus_from_qdev(dev);
+    qdev_init_nofail(dev);
+    if (addr != (target_phys_addr_t)-1) {
+        sysbus_mmio_map(bus, 0, addr);
+    }
+    sysbus_connect_irq(bus, 0, irq);
+
+    return dev;
+}
+
+static int exynos4210_uart_init(SysBusDevice *dev)
+{
+    Exynos4210UartState *s = FROM_SYSBUS(Exynos4210UartState, dev);
+
+    /* memory mapping */
+    memory_region_init_io(&s->iomem, &exynos4210_uart_ops, s, "exynos4210.uart",
+                          EXYNOS4210_UART_REGS_MEM_SIZE);
+    sysbus_init_mmio(dev, &s->iomem);
+
+    sysbus_init_irq(dev, &s->irq);
+
+    qemu_chr_add_handlers(s->chr, exynos4210_uart_can_receive,
+                          exynos4210_uart_receive, exynos4210_uart_event, s);
+
+    return 0;
+}
+
+static SysBusDeviceInfo exynos4210_uart_info = {
+    .init       = exynos4210_uart_init,
+    .qdev.name  = "exynos4210.uart",
+    .qdev.size  = sizeof(Exynos4210UartState),
+    .qdev.vmsd  = &vmstate_exynos4210_uart,
+    .qdev.reset = exynos4210_uart_reset,
+    .qdev.props = (Property[]) {
+        DEFINE_PROP_CHR("chardev", Exynos4210UartState, chr),
+        DEFINE_PROP_UINT32("channel", Exynos4210UartState, channel, 0),
+        DEFINE_PROP_UINT32("rx-size", Exynos4210UartState, rx.size, 16),
+        DEFINE_PROP_UINT32("tx-size", Exynos4210UartState, tx.size, 16),
+        DEFINE_PROP_END_OF_LIST(),
+    }
+};
+
+static void exynos4210_uart_register(void)
+{
+    sysbus_register_withprop(&exynos4210_uart_info);
+}
+
+device_init(exynos4210_uart_register)