drivers/tty/serial/tegra-tcu.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (c) 2018, NVIDIA CORPORATION.  All rights reserved.
   4  */
   5
   6 #include <linux/console.h>
   7 #include <linux/mailbox_client.h>
   8 #include <linux/module.h>
   9 #include <linux/of.h>
  10 #include <linux/of_device.h>
  11 #include <linux/platform_device.h>
  12 #include <linux/serial.h>
  13 #include <linux/serial_core.h>
  14 #include <linux/slab.h>
  15 #include <linux/tty.h>
  16 #include <linux/tty_flip.h>
  17
  18 #define TCU_MBOX_BYTE(i, x)                     ((x) << (i * 8))
  19 #define TCU_MBOX_BYTE_V(x, i)                   (((x) >> (i * 8)) & 0xff)
  20 #define TCU_MBOX_NUM_BYTES(x)                   ((x) << 24)
  21 #define TCU_MBOX_NUM_BYTES_V(x)                 (((x) >> 24) & 0x3)
  22
  23 struct tegra_tcu {
  24         struct uart_driver driver;
  25 #if IS_ENABLED(CONFIG_SERIAL_TEGRA_TCU_CONSOLE)
  26         struct console console;
  27 #endif
  28         struct uart_port port;
  29
  30         struct mbox_client tx_client, rx_client;
  31         struct mbox_chan *tx, *rx;
  32 };
  33
  34 static unsigned int tegra_tcu_uart_tx_empty(struct uart_port *port)
  35 {
  36         return TIOCSER_TEMT;
  37 }
  38
  39 static void tegra_tcu_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
  40 {
  41 }
  42
  43 static unsigned int tegra_tcu_uart_get_mctrl(struct uart_port *port)
  44 {
  45         return 0;
  46 }
  47
  48 static void tegra_tcu_uart_stop_tx(struct uart_port *port)
  49 {
  50 }
  51
  52 static void tegra_tcu_write_one(struct tegra_tcu *tcu, u32 value,
  53                                 unsigned int count)
  54 {
  55         void *msg;
  56
  57         value |= TCU_MBOX_NUM_BYTES(count);
  58         msg = (void *)(unsigned long)value;
  59         mbox_send_message(tcu->tx, msg);
  60         mbox_flush(tcu->tx, 1000);
  61 }
  62
  63 static void tegra_tcu_write(struct tegra_tcu *tcu, const char *s,
  64                             unsigned int count)
  65 {
  66         unsigned int written = 0, i = 0;
  67         bool insert_nl = false;
  68         u32 value = 0;
  69
  70         while (i < count) {
  71                 if (insert_nl) {
  72                         value |= TCU_MBOX_BYTE(written++, '\n');
  73                         insert_nl = false;
  74                         i++;
  75                 } else if (s[i] == '\n') {
  76                         value |= TCU_MBOX_BYTE(written++, '\r');
  77                         insert_nl = true;
  78                 } else {
  79                         value |= TCU_MBOX_BYTE(written++, s[i++]);
  80                 }
  81
  82                 if (written == 3) {
  83                         tegra_tcu_write_one(tcu, value, 3);
  84                         value = written = 0;
  85                 }
  86         }
  87
  88         if (written)
  89                 tegra_tcu_write_one(tcu, value, written);
  90 }
  91
  92 static void tegra_tcu_uart_start_tx(struct uart_port *port)
  93 {
  94         struct tegra_tcu *tcu = port->private_data;
  95         struct circ_buf *xmit = &port->state->xmit;
  96         unsigned long count;
  97
  98         for (;;) {
  99                 count = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
 100                 if (!count)
 101                         break;
 102
 103                 tegra_tcu_write(tcu, &xmit->buf[xmit->tail], count);
 104                 xmit->tail = (xmit->tail + count) & (UART_XMIT_SIZE - 1);
 105         }
 106
 107         uart_write_wakeup(port);
 108 }
 109
 110 static void tegra_tcu_uart_stop_rx(struct uart_port *port)
 111 {
 112 }
 113
 114 static void tegra_tcu_uart_break_ctl(struct uart_port *port, int ctl)
 115 {
 116 }
 117
 118 static int tegra_tcu_uart_startup(struct uart_port *port)
 119 {
 120         return 0;
 121 }
 122
 123 static void tegra_tcu_uart_shutdown(struct uart_port *port)
 124 {
 125 }
 126
 127 static void tegra_tcu_uart_set_termios(struct uart_port *port,
 128                                        struct ktermios *new,
 129                                        struct ktermios *old)
 130 {
 131 }
 132
 133 static const struct uart_ops tegra_tcu_uart_ops = {
 134         .tx_empty = tegra_tcu_uart_tx_empty,
 135         .set_mctrl = tegra_tcu_uart_set_mctrl,
 136         .get_mctrl = tegra_tcu_uart_get_mctrl,
 137         .stop_tx = tegra_tcu_uart_stop_tx,
 138         .start_tx = tegra_tcu_uart_start_tx,
 139         .stop_rx = tegra_tcu_uart_stop_rx,
 140         .break_ctl = tegra_tcu_uart_break_ctl,
 141         .startup = tegra_tcu_uart_startup,
 142         .shutdown = tegra_tcu_uart_shutdown,
 143         .set_termios = tegra_tcu_uart_set_termios,
 144 };
 145
 146 #if IS_ENABLED(CONFIG_SERIAL_TEGRA_TCU_CONSOLE)
 147 static void tegra_tcu_console_write(struct console *cons, const char *s,
 148                                     unsigned int count)
 149 {
 150         struct tegra_tcu *tcu = container_of(cons, struct tegra_tcu, console);
 151
 152         tegra_tcu_write(tcu, s, count);
 153 }
 154
 155 static int tegra_tcu_console_setup(struct console *cons, char *options)
 156 {
 157         return 0;
 158 }
 159 #endif
 160
 161 static void tegra_tcu_receive(struct mbox_client *cl, void *msg)
 162 {
 163         struct tegra_tcu *tcu = container_of(cl, struct tegra_tcu, rx_client);
 164         struct tty_port *port = &tcu->port.state->port;
 165         u32 value = (u32)(unsigned long)msg;
 166         unsigned int num_bytes, i;
 167
 168         num_bytes = TCU_MBOX_NUM_BYTES_V(value);
 169
 170         for (i = 0; i < num_bytes; i++)
 171                 tty_insert_flip_char(port, TCU_MBOX_BYTE_V(value, i),
 172                                      TTY_NORMAL);
 173
 174         tty_flip_buffer_push(port);
 175 }
 176
 177 static int tegra_tcu_probe(struct platform_device *pdev)
 178 {
 179         struct uart_port *port;
 180         struct tegra_tcu *tcu;
 181         int err;
 182
 183         tcu = devm_kzalloc(&pdev->dev, sizeof(*tcu), GFP_KERNEL);
 184         if (!tcu)
 185                 return -ENOMEM;
 186
 187         tcu->tx_client.dev = &pdev->dev;
 188         tcu->rx_client.dev = &pdev->dev;
 189         tcu->rx_client.rx_callback = tegra_tcu_receive;
 190
 191         tcu->tx = mbox_request_channel_byname(&tcu->tx_client, "tx");
 192         if (IS_ERR(tcu->tx)) {
 193                 err = PTR_ERR(tcu->tx);
 194                 dev_err(&pdev->dev, "failed to get tx mailbox: %d\n", err);
 195                 return err;
 196         }
 197
 198         tcu->rx = mbox_request_channel_byname(&tcu->rx_client, "rx");
 199         if (IS_ERR(tcu->rx)) {
 200                 err = PTR_ERR(tcu->rx);
 201                 dev_err(&pdev->dev, "failed to get rx mailbox: %d\n", err);
 202                 goto free_tx;
 203         }
 204
 205 #if IS_ENABLED(CONFIG_SERIAL_TEGRA_TCU_CONSOLE)
 206         /* setup the console */
 207         strcpy(tcu->console.name, "ttyTCU");
 208         tcu->console.device = uart_console_device;
 209         tcu->console.flags = CON_PRINTBUFFER | CON_ANYTIME;
 210         tcu->console.index = -1;
 211         tcu->console.write = tegra_tcu_console_write;
 212         tcu->console.setup = tegra_tcu_console_setup;
 213         tcu->console.data = &tcu->driver;
 214 #endif
 215
 216         /* setup the driver */
 217         tcu->driver.owner = THIS_MODULE;
 218         tcu->driver.driver_name = "tegra-tcu";
 219         tcu->driver.dev_name = "ttyTCU";
 220 #if IS_ENABLED(CONFIG_SERIAL_TEGRA_TCU_CONSOLE)
 221         tcu->driver.cons = &tcu->console;
 222 #endif
 223         tcu->driver.nr = 1;
 224
 225         err = uart_register_driver(&tcu->driver);
 226         if (err) {
 227                 dev_err(&pdev->dev, "failed to register UART driver: %d\n",
 228                         err);
 229                 goto free_rx;
 230         }
 231
 232         /* setup the port */
 233         port = &tcu->port;
 234         spin_lock_init(&port->lock);
 235         port->dev = &pdev->dev;
 236         port->type = PORT_TEGRA_TCU;
 237         port->ops = &tegra_tcu_uart_ops;
 238         port->fifosize = 1;
 239         port->iotype = UPIO_MEM;
 240         port->flags = UPF_BOOT_AUTOCONF;
 241         port->private_data = tcu;
 242
 243         err = uart_add_one_port(&tcu->driver, port);
 244         if (err) {
 245                 dev_err(&pdev->dev, "failed to add UART port: %d\n", err);
 246                 goto unregister_uart;
 247         }
 248
 249         platform_set_drvdata(pdev, tcu);
 250 #if IS_ENABLED(CONFIG_SERIAL_TEGRA_TCU_CONSOLE)
 251         register_console(&tcu->console);
 252 #endif
 253
 254         return 0;
 255
 256 unregister_uart:
 257         uart_unregister_driver(&tcu->driver);
 258 free_rx:
 259         mbox_free_channel(tcu->rx);
 260 free_tx:
 261         mbox_free_channel(tcu->tx);
 262
 263         return err;
 264 }
 265
 266 static int tegra_tcu_remove(struct platform_device *pdev)
 267 {
 268         struct tegra_tcu *tcu = platform_get_drvdata(pdev);
 269
 270 #if IS_ENABLED(CONFIG_SERIAL_TEGRA_TCU_CONSOLE)
 271         unregister_console(&tcu->console);
 272 #endif
 273         uart_remove_one_port(&tcu->driver, &tcu->port);
 274         uart_unregister_driver(&tcu->driver);
 275         mbox_free_channel(tcu->rx);
 276         mbox_free_channel(tcu->tx);
 277
 278         return 0;
 279 }
 280
 281 static const struct of_device_id tegra_tcu_match[] = {
 282         { .compatible = "nvidia,tegra194-tcu" },
 283         { }
 284 };
 285
 286 static struct platform_driver tegra_tcu_driver = {
 287         .driver = {
 288                 .name = "tegra-tcu",
 289                 .of_match_table = tegra_tcu_match,
 290         },
 291         .probe = tegra_tcu_probe,
 292         .remove = tegra_tcu_remove,
 293 };
 294 module_platform_driver(tegra_tcu_driver);
 295
 296 MODULE_AUTHOR("Mikko Perttunen <mperttunen@nvidia.com>");
 297 MODULE_LICENSE("GPL v2");
 298 MODULE_DESCRIPTION("NVIDIA Tegra Combined UART driver");