Setup project skeleton

16 files changed, 958 insertions, 0 deletions

diff --git a/src/drv/ps1/sio/CMakeLists.txt b/src/drv/ps1/sio/CMakeLists.txt
new file mode 100644
index 0000000..f382e08
--- /dev/null
+++ b/src/drv/ps1/sio/CMakeLists.txt
@@ -0,0 +1,22 @@
+# wnix, a Unix-like operating system for WebAssembly applications.
+# Copyright (C) 2025  Xavier Del Campo Romero
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 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 Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+add_library(drv_ps1_sio)
+add_subdirectory(src)
+target_include_directories(drv_ps1_sio PUBLIC include PRIVATE private_include)
+target_link_libraries(drv_ps1_sio
+    PUBLIC c
+    PRIVATE drv drv_ps1_bios drv_ps1_cpu drv_ps1_irq)
diff --git a/src/drv/ps1/sio/include/drv/ps1/sio.h b/src/drv/ps1/sio/include/drv/ps1/sio.h
new file mode 100644
index 0000000..3fabadd
--- /dev/null
+++ b/src/drv/ps1/sio/include/drv/ps1/sio.h
@@ -0,0 +1,28 @@
+/*
+ * wnix, a Unix-like operating system for WebAssembly applications.
+ * Copyright (C) 2025  Xavier Del Campo Romero
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef DRV_PS1_SIO_H
+#define DRV_PS1_SIO_H
+
+#include <drv/event.h>
+
+struct drv_ps1_sio *drv_ps1_sio_init(const struct drv_event *ev);
+int drv_ps1_sio_update(struct drv_ps1_sio *sio);
+void drv_ps1_sio_free(struct drv_ps1_sio *sio);
+
+#endif
diff --git a/src/drv/ps1/sio/private_include/drv/ps1/sio/ops.h b/src/drv/ps1/sio/private_include/drv/ps1/sio/ops.h
new file mode 100644
index 0000000..a481fa9
--- /dev/null
+++ b/src/drv/ps1/sio/private_include/drv/ps1/sio/ops.h
@@ -0,0 +1,31 @@
+/*
+ * wnix, a Unix-like operating system for WebAssembly applications.
+ * Copyright (C) 2025  Xavier Del Campo Romero
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef DRV_PS1_SIO_OPS_H
+#define DRV_PS1_SIO_OPS_H
+
+#include <drv/event.h>
+#include <sys/types.h>
+
+int drv_ps1_sio_read(void *buf, size_t n, off_t offset,
+    const struct drv_event_done *done, void *args);
+int drv_ps1_sio_read_nb(void *buf, size_t n, void *args);
+int drv_ps1_sio_write(const void *buf, size_t n,
+    const struct drv_event_done *done, void *args);
+
+#endif
diff --git a/src/drv/ps1/sio/private_include/drv/ps1/sio/regs.h b/src/drv/ps1/sio/private_include/drv/ps1/sio/regs.h
new file mode 100644
index 0000000..16b2bca
--- /dev/null
+++ b/src/drv/ps1/sio/private_include/drv/ps1/sio/regs.h
@@ -0,0 +1,136 @@
+/*
+ * wnix, a Unix-like operating system for WebAssembly applications.
+ * Copyright (C) 2025  Xavier Del Campo Romero
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef DRV_PS1_SIO_REGS_H
+#define DRV_PS1_SIO_REGS_H
+
+#include <stdint.h>
+
+struct sio_tx_data
+{
+    uint32_t value :8, :24;
+};
+
+struct sio_rx_data
+{
+    uint8_t values[4];
+};
+
+union sio_stat
+{
+    struct
+    {
+        uint32_t
+            tx_ready_started :1,
+            rx_fifo_not_empty :1,
+            tx_ready_finished :1,
+            rx_parity_error :1,
+            rx_fifo_overrun :1,
+            rx_bad_stp :1,
+            rx_inverted :1,
+            dsr :1,
+            cts :1,
+            irqreq :1,
+            :1,
+            baudrate :15, :6;
+    } bits;
+
+    uint32_t mask;
+};
+
+union sio_mode
+{
+    struct
+    {
+        uint16_t
+            baudrate_mul :2,
+            len :2,
+            parity_en :1,
+            parity_odd :1,
+            stplen :2,
+            :8;
+    } bits;
+
+    uint16_t mask;
+};
+
+union sio_ctrl
+{
+    struct
+    {
+        uint16_t
+            tx_en :1,
+            dtr :1,
+            rx_en :1,
+            tx_invert :1,
+            ack :1,
+            rts :1,
+            reset :1,
+            :1,
+            rx_int_mode :2,
+            tx_int_en :1,
+            rx_int_en :1,
+            dsr_int_en :1,
+            :3;
+    } bits;
+
+    uint16_t mask;
+};
+
+enum
+{
+    SIO_CTRL_RX_INT_1,
+    SIO_CTRL_RX_INT_2,
+    SIO_CTRL_RX_INT_3,
+    SIO_CTRL_RX_INT_4
+};
+
+enum
+{
+    SIO_MODE_FACTOR_STOP,
+    SIO_MODE_FACTOR_MUL1,
+    SIO_MODE_FACTOR_MUL16,
+    SIO_MODE_FACTOR_MUL64
+};
+
+enum
+{
+    SIO_MODE_LEN_5,
+    SIO_MODE_LEN_6,
+    SIO_MODE_LEN_7,
+    SIO_MODE_LEN_8
+};
+
+enum
+{
+    SIO_MODE_STP_RESERVED,
+    SIO_MODE_STP_1,
+    SIO_MODE_STP_1_5,
+    SIO_MODE_STP_2,
+};
+
+#define SIO_BASE 0x1f801050
+#define SIO_REG(n) (SIO_BASE + n)
+#define SIO_TX_DATA ((volatile struct sio_tx_data *)SIO_REG(0))
+#define SIO_RX_DATA ((const volatile struct sio_rx_data *)SIO_REG(0))
+#define SIO_STAT ((const volatile union sio_stat *)SIO_REG(4))
+#define SIO_MODE ((volatile union sio_mode *)SIO_REG(8))
+#define SIO_CTRL ((volatile union sio_ctrl *)SIO_REG(10))
+#define SIO_BAUD (*(volatile uint16_t *)SIO_REG(14))
+
+#endif
diff --git a/src/drv/ps1/sio/private_include/drv/ps1/sio/routines.h b/src/drv/ps1/sio/private_include/drv/ps1/sio/routines.h
new file mode 100644
index 0000000..f5b97da
--- /dev/null
+++ b/src/drv/ps1/sio/private_include/drv/ps1/sio/routines.h
@@ -0,0 +1,27 @@
+/*
+ * wnix, a Unix-like operating system for WebAssembly applications.
+ * Copyright (C) 2025  Xavier Del Campo Romero
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef DRV_PS1_SIO_ROUTINES_H
+#define DRV_PS1_SIO_ROUTINES_H
+
+#include <drv/ps1/sio/types.h>
+
+int drv_ps1_sio_irq(void);
+int drv_ps1_sio_next(struct sio_fifo *f);
+
+#endif
diff --git a/src/drv/ps1/sio/private_include/drv/ps1/sio/types.h b/src/drv/ps1/sio/private_include/drv/ps1/sio/types.h
new file mode 100644
index 0000000..87dd412
--- /dev/null
+++ b/src/drv/ps1/sio/private_include/drv/ps1/sio/types.h
@@ -0,0 +1,65 @@
+/*
+ * wnix, a Unix-like operating system for WebAssembly applications.
+ * Copyright (C) 2025  Xavier Del Campo Romero
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef DRV_PS1_SIO_TYPES_H
+#define DRV_PS1_SIO_TYPES_H
+
+#include <drv/event.h>
+#include <stdbool.h>
+
+struct sio_req
+{
+    union
+    {
+        struct sio_req_r
+        {
+            void *buf;
+            size_t n;
+        } r;
+
+        struct sio_req_w
+        {
+            const void *buf;
+            size_t n;
+        } w;
+    } u;
+
+    int (*f)(void);
+    struct drv_event_done done;
+    struct sio_req *next;
+};
+
+struct sio_fifo
+{
+    char buf[192];
+    size_t proc, pend;
+    struct sio_req *head, *tail;
+    int (*next)(void);
+};
+
+struct drv_ps1_sio
+{
+    bool init;
+    int event;
+    struct sio_fifo rx, tx;
+    struct drv_event ev;
+};
+
+extern struct drv_ps1_sio drv_ps1_sio;
+
+#endif
diff --git a/src/drv/ps1/sio/src/CMakeLists.txt b/src/drv/ps1/sio/src/CMakeLists.txt
new file mode 100644
index 0000000..1bcf5cf
--- /dev/null
+++ b/src/drv/ps1/sio/src/CMakeLists.txt
@@ -0,0 +1,29 @@
+# wnix, a Unix-like operating system for WebAssembly applications.
+# Copyright (C) 2025  Xavier Del Campo Romero
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 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 Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+target_sources(drv_ps1_sio PRIVATE
+    free.c
+    globals.c
+    init.c
+    irq.c
+    next.c
+    read.c
+    read_nb.c
+    update.c
+    write.c
+)
+
+target_link_libraries(drv_ps1_sio PRIVATE kprintf)
diff --git a/src/drv/ps1/sio/src/free.c b/src/drv/ps1/sio/src/free.c
new file mode 100644
index 0000000..5c506d0
--- /dev/null
+++ b/src/drv/ps1/sio/src/free.c
@@ -0,0 +1,23 @@
+/*
+ * wnix, a Unix-like operating system for WebAssembly applications.
+ * Copyright (C) 2025  Xavier Del Campo Romero
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <drv/ps1/sio.h>
+
+void drv_ps1_sio_free(struct drv_ps1_sio *const sio)
+{
+}
diff --git a/src/drv/ps1/sio/src/globals.c b/src/drv/ps1/sio/src/globals.c
new file mode 100644
index 0000000..35c72b8
--- /dev/null
+++ b/src/drv/ps1/sio/src/globals.c
@@ -0,0 +1,21 @@
+/*
+ * wnix, a Unix-like operating system for WebAssembly applications.
+ * Copyright (C) 2025  Xavier Del Campo Romero
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <drv/ps1/sio/types.h>
+
+struct drv_ps1_sio drv_ps1_sio;
diff --git a/src/drv/ps1/sio/src/init.c b/src/drv/ps1/sio/src/init.c
new file mode 100644
index 0000000..6bf44fc
--- /dev/null
+++ b/src/drv/ps1/sio/src/init.c
@@ -0,0 +1,70 @@
+/*
+ * wnix, a Unix-like operating system for WebAssembly applications.
+ * Copyright (C) 2025  Xavier Del Campo Romero
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <drv/ps1/sio.h>
+#include <drv/ps1/sio/ops.h>
+#include <drv/ps1/sio/regs.h>
+#include <drv/ps1/sio/routines.h>
+#include <drv/ps1/sio/types.h>
+#include <drv/ps1/bios.h>
+#include <drv/ps1/cpu.h>
+#include <drv/ps1/irq.h>
+#include <drv/event.h>
+
+struct drv_ps1_sio *drv_ps1_sio_init(const struct drv_event *const ev)
+{
+    const unsigned long baudrate = 115200ul;
+
+    SIO_CTRL->bits.reset = 1;
+    SIO_BAUD = DRV_PS1_CPU_F / (16 * baudrate);
+    SIO_MODE->mask = (const union sio_mode)
+    {
+        .bits =
+        {
+            .baudrate_mul = SIO_MODE_FACTOR_MUL16,
+            .stplen = SIO_MODE_STP_1,
+            .len = SIO_MODE_LEN_8
+        }
+    }.mask;
+
+    SIO_CTRL->mask = (const union sio_ctrl)
+    {
+        .bits =
+        {
+            .rx_int_mode = SIO_CTRL_RX_INT_1,
+            .rx_int_en = 1,
+            .tx_en = 1,
+            .rx_en = 1,
+            .rts = 1,
+            .dtr = 1
+        }
+    }.mask;
+
+    static struct drv_ps1_irq_src src =
+    {
+        .mask = 1 << IRQ_SIO,
+        .fn = drv_ps1_sio_irq
+    };
+
+    if (drv_ps1_irq_set(&src))
+        return NULL;
+
+    I_MASK->bits.sio = 1;
+    drv_ps1_sio.ev = *ev;
+    return &drv_ps1_sio;
+}
diff --git a/src/drv/ps1/sio/src/irq.c b/src/drv/ps1/sio/src/irq.c
new file mode 100644
index 0000000..5a19d83
--- /dev/null
+++ b/src/drv/ps1/sio/src/irq.c
@@ -0,0 +1,71 @@
+/*
+ * wnix, a Unix-like operating system for WebAssembly applications.
+ * Copyright (C) 2025  Xavier Del Campo Romero
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <drv/ps1/sio.h>
+#include <drv/ps1/sio/ops.h>
+#include <drv/ps1/sio/regs.h>
+#include <drv/ps1/sio/routines.h>
+#include <drv/ps1/sio/types.h>
+#include <drv/ps1/bios.h>
+#include <drv/ps1/cpu.h>
+#include <drv/ps1/irq.h>
+#include <drv/event.h>
+
+int irq_sio_overrun;
+
+static int read_rx(struct sio_fifo *const f)
+{
+    const unsigned char v = *SIO_RX_DATA->values;
+    size_t n = f->pend + 1;
+
+    if (n >= sizeof f->buf)
+        n = 0;
+
+    if (n == f->proc)
+    {
+        irq_sio_overrun = 1;
+        return -1;
+    }
+
+    f->buf[f->pend = n] = v;
+    return 0;
+}
+
+volatile unsigned sio_read;
+volatile int sw_overrun;
+
+int drv_ps1_sio_irq(void)
+{
+    SIO_CTRL->bits.rts = 0;
+
+    while (SIO_STAT->bits.rx_fifo_not_empty)
+    {
+        if (read_rx(&drv_ps1_sio.rx))
+        {
+            sw_overrun = 1;
+            break;
+        }
+
+        sio_read++;
+    }
+
+    SIO_CTRL->bits.rts = 1;
+    I_STAT->bits.sio = 0;
+    SIO_CTRL->bits.ack = 1;
+    return 0;
+}
diff --git a/src/drv/ps1/sio/src/next.c b/src/drv/ps1/sio/src/next.c
new file mode 100644
index 0000000..4c330ab
--- /dev/null
+++ b/src/drv/ps1/sio/src/next.c
@@ -0,0 +1,34 @@
+/*
+ * wnix, a Unix-like operating system for WebAssembly applications.
+ * Copyright (C) 2025  Xavier Del Campo Romero
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <drv/ps1/sio.h>
+#include <drv/ps1/sio/routines.h>
+#include <drv/ps1/sio/types.h>
+#include <stddef.h>
+#include <stdlib.h>
+
+int drv_ps1_sio_next(struct sio_fifo *const f)
+{
+    struct sio_req *const next = f->head->next;
+
+    free(f->head);
+
+    f->next = next ? next->f : NULL;
+    f->head = next;
+    return 0;
+}
diff --git a/src/drv/ps1/sio/src/read.c b/src/drv/ps1/sio/src/read.c
new file mode 100644
index 0000000..e13ad29
--- /dev/null
+++ b/src/drv/ps1/sio/src/read.c
@@ -0,0 +1,125 @@
+/*
+ * wnix, a Unix-like operating system for WebAssembly applications.
+ * Copyright (C) 2025  Xavier Del Campo Romero
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <drv/ps1/sio/ops.h>
+#include <drv/ps1/sio/regs.h>
+#include <drv/ps1/sio/routines.h>
+#include <drv/ps1/sio/types.h>
+#include <drv/ps1/bios.h>
+#include <drv/ps1/irq.h>
+#include <drv/event.h>
+#include <kprintf.h>
+#include <sys/types.h>
+#include <errno.h>
+#include <stdlib.h>
+
+static int load(void);
+
+static int check(void)
+{
+    struct drv_ps1_sio *const s = &drv_ps1_sio;
+    struct sio_fifo *const f = &s->rx;
+    struct sio_req *const req = f->head;
+    struct sio_req_r *const r = &req->u.r;
+
+    if (!r->n)
+    {
+        const struct drv_event_done *const d = &req->done;
+
+        if (d->f && d->f(SUCCESS, d->args))
+            return -1;
+
+        return drv_ps1_sio_next(f);
+    }
+
+    f->next = load;
+    return 0;
+}
+
+static void read_fifo(struct drv_ps1_sio *const s)
+{
+    struct sio_fifo *const f = &s->rx;
+    struct sio_req *const req = f->head;
+    struct sio_req_r *const r = &req->u.r;
+    char *p = r->buf;
+
+    I_MASK->bits.sio = 0;
+    SIO_CTRL->bits.rts = 0;
+
+    while (r->n)
+    {
+        if (f->pend == f->proc)
+            break;
+
+        size_t n = f->proc + 1;
+
+        if (n >= sizeof f->buf)
+            n = 0;
+
+        *p++ = f->buf[f->proc = n];
+        r->buf = p;
+        r->n--;
+    }
+
+    SIO_CTRL->bits.rts = 1;
+    I_MASK->bits.sio = 1;
+}
+
+static int load(void)
+{
+    struct drv_ps1_sio *const s = &drv_ps1_sio;
+    struct sio_fifo *const f = &s->rx;
+    struct sio_req_r *const r = &f->head->u.r;
+
+    read_fifo(s);
+
+    if (!r->n)
+        f->next = check;
+
+    return 0;
+}
+
+int drv_ps1_sio_read(void *const buf, const size_t n, const off_t offset,
+    const struct drv_event_done *const done, void *const args)
+{
+    struct drv_ps1_sio *const s = &drv_ps1_sio;
+    struct sio_fifo *const f = &s->rx;
+    struct sio_req *const req = malloc(sizeof *req);
+
+    if (!req)
+        return -1;
+
+    *req = (const struct sio_req)
+    {
+        .f = load,
+        .done = *done,
+        .u.r =
+        {
+            .buf = buf,
+            .n = n
+        }
+    };
+
+    if (!f->head)
+        f->head = req;
+    else
+        f->tail->next = req;
+
+    f->tail = req;
+    return 0;
+}
diff --git a/src/drv/ps1/sio/src/read_nb.c b/src/drv/ps1/sio/src/read_nb.c
new file mode 100644
index 0000000..755c5cf
--- /dev/null
+++ b/src/drv/ps1/sio/src/read_nb.c
@@ -0,0 +1,61 @@
+/*
+ * wnix, a Unix-like operating system for WebAssembly applications.
+ * Copyright (C) 2025  Xavier Del Campo Romero
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <drv/ps1/sio/ops.h>
+#include <drv/ps1/sio/regs.h>
+#include <drv/ps1/sio/routines.h>
+#include <drv/ps1/sio/types.h>
+#include <drv/ps1/irq.h>
+#include <drv/ps1/bios.h>
+#include <drv/event.h>
+#include <kprintf.h>
+#include <sys/types.h>
+
+static int read_fifo(char *buf, size_t n)
+{
+    int ret = 0;
+    struct drv_ps1_sio *const s = &drv_ps1_sio;
+    struct sio_fifo *const f = &s->rx;
+
+    I_MASK->bits.sio = 0;
+    SIO_CTRL->bits.rts = 0;
+
+    while (n)
+    {
+        if (f->pend == f->proc)
+            break;
+
+        size_t m = f->proc + 1;
+
+        if (m >= sizeof f->buf)
+            m = 0;
+
+        *buf++ = f->buf[f->proc = m];
+        n--;
+        ret++;
+    }
+
+    SIO_CTRL->bits.rts = 1;
+    I_MASK->bits.sio = 1;
+    return ret;
+}
+
+int drv_ps1_sio_read_nb(void *const buf, const size_t n, void *const args)
+{
+    return read_fifo(buf, n);
+}
diff --git a/src/drv/ps1/sio/src/update.c b/src/drv/ps1/sio/src/update.c
new file mode 100644
index 0000000..eac875c
--- /dev/null
+++ b/src/drv/ps1/sio/src/update.c
@@ -0,0 +1,98 @@
+/*
+ * wnix, a Unix-like operating system for WebAssembly applications.
+ * Copyright (C) 2025  Xavier Del Campo Romero
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <drv/ps1/sio.h>
+#include <drv/ps1/sio/ops.h>
+#include <drv/ps1/sio/regs.h>
+#include <drv/ps1/sio/routines.h>
+#include <drv/ps1/sio/types.h>
+#include <drv/event.h>
+#include <kprintf.h>
+#include <stddef.h>
+#include <stdbool.h>
+
+static int init(struct drv_ps1_sio *const s)
+{
+    if (s->init)
+        return 0;
+
+    const struct drv_event *const ev = &s->ev;
+    static const struct drv_event_ops ops =
+    {
+        .read = drv_ps1_sio_read,
+        .read_nb = drv_ps1_sio_read_nb,
+        .write = drv_ps1_sio_write
+    };
+
+    if (ev->status("ttyS0", &ops, true, 0660, ev->args))
+        return -1;
+
+    s->init = true;
+    return 0;
+}
+
+static int rx(struct drv_ps1_sio *const s)
+{
+    struct sio_fifo *const f = &s->rx;
+
+    if (f->next)
+        return f->next();
+    else if (f->head)
+        f->next = f->head->f;
+
+    return 0;
+}
+
+static void write_tx(struct sio_fifo *const f)
+{
+    if (f->proc == f->pend)
+        return;
+
+    size_t n = f->proc + 1;
+
+    if (n >= sizeof f->buf)
+        n = 0;
+
+    SIO_TX_DATA->value = f->buf[f->proc = n];
+}
+
+static int tx(struct drv_ps1_sio *const s)
+{
+    struct sio_fifo *const f = &s->tx;
+
+    if (SIO_STAT->bits.tx_ready_started)
+        write_tx(f);
+
+    if (f->next)
+        return f->next();
+    else if (f->head)
+        f->next = f->head->f;
+
+    return 0;
+}
+
+int drv_ps1_sio_update(struct drv_ps1_sio *const s)
+{
+    if (SIO_STAT->bits.rx_fifo_overrun)
+        SIO_CTRL->bits.ack = 1;
+
+    if (init(s) || rx(s) || tx(s))
+        return -1;
+
+    return 0;
+}
diff --git a/src/drv/ps1/sio/src/write.c b/src/drv/ps1/sio/src/write.c
new file mode 100644
index 0000000..942456f
--- /dev/null
+++ b/src/drv/ps1/sio/src/write.c
@@ -0,0 +1,117 @@
+/*
+ * wnix, a Unix-like operating system for WebAssembly applications.
+ * Copyright (C) 2025  Xavier Del Campo Romero
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <drv/ps1/sio/ops.h>
+#include <drv/ps1/sio/routines.h>
+#include <drv/ps1/sio/types.h>
+#include <drv/ps1/bios.h>
+#include <drv/event.h>
+#include <kprintf.h>
+#include <sys/types.h>
+#include <errno.h>
+#include <stddef.h>
+#include <stdlib.h>
+
+static int store(void);
+
+static void write_fifo(struct drv_ps1_sio *const s)
+{
+    struct sio_fifo *const f = &s->tx;
+    struct sio_req *const r = f->head;
+    struct sio_req_w *const w = &r->u.w;
+    const char *p = w->buf;
+
+    while (w->n)
+    {
+        size_t n = f->pend + 1;
+
+        if (n >= sizeof f->buf)
+            n = 0;
+        else if (n == f->proc)
+            break;
+
+        f->buf[f->pend = n] = *p++;
+        w->buf = p;
+        w->n--;
+    }
+}
+
+static int check(void)
+{
+    struct drv_ps1_sio *const s = &drv_ps1_sio;
+    struct sio_fifo *const f = &s->tx;
+    struct sio_req *const r = f->head;
+    struct sio_req_w *const w = &r->u.w;
+
+    if (!w->n)
+    {
+        const struct drv_event_done *const d = &r->done;
+
+        if (d->f && d->f(SUCCESS, d->args))
+            return -1;
+
+        return drv_ps1_sio_next(f);
+    }
+
+    f->next = store;
+    return 0;
+}
+
+static int store(void)
+{
+    struct drv_ps1_sio *const s = &drv_ps1_sio;
+    struct sio_fifo *const f = &s->tx;
+    struct sio_req_w *const w = &f->head->u.w;
+
+    write_fifo(s);
+
+    if (!w->n)
+        f->next = check;
+
+    return 0;
+}
+
+int drv_ps1_sio_write(const void *const buf, const size_t n,
+    const struct drv_event_done *const done, void *const args)
+{
+    struct drv_ps1_sio *const s = &drv_ps1_sio;
+    struct sio_fifo *const f = &s->tx;
+    struct sio_req *const req = malloc(sizeof *req);
+
+    if (!req)
+        return -1;
+
+    *req = (const struct sio_req)
+    {
+        .f = store,
+        .done = *done,
+        .u.w =
+        {
+            .buf = buf,
+            .n = n
+        }
+    };
+
+    if (!f->head)
+        f->head = req;
+    else
+        f->tail->next = req;
+
+    f->tail = req;
+    return 0;
+}