diff options
Diffstat (limited to 'drivers/serial/serial_xen.c')
| -rw-r--r-- | drivers/serial/serial_xen.c | 182 |
1 files changed, 182 insertions, 0 deletions
diff --git a/drivers/serial/serial_xen.c b/drivers/serial/serial_xen.c new file mode 100644 index 00000000000..ba6504b9479 --- /dev/null +++ b/drivers/serial/serial_xen.c @@ -0,0 +1,182 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * (C) 2018 NXP + * (C) 2020 EPAM Systems Inc. + */ +#include <common.h> +#include <cpu_func.h> +#include <dm.h> +#include <serial.h> +#include <watchdog.h> + +#include <linux/bug.h> + +#include <xen/hvm.h> +#include <xen/events.h> + +#include <xen/interface/sched.h> +#include <xen/interface/hvm/hvm_op.h> +#include <xen/interface/hvm/params.h> +#include <xen/interface/io/console.h> +#include <xen/interface/io/ring.h> + +DECLARE_GLOBAL_DATA_PTR; + +u32 console_evtchn; + +/* + * struct xen_uart_priv - Structure representing a Xen UART info + * @intf: Console I/O interface for Xen guest OSes + * @evtchn: Console event channel + */ +struct xen_uart_priv { + struct xencons_interface *intf; + u32 evtchn; +}; + +int xen_serial_setbrg(struct udevice *dev, int baudrate) +{ + return 0; +} + +static int xen_serial_probe(struct udevice *dev) +{ + struct xen_uart_priv *priv = dev_get_priv(dev); + u64 val = 0; + unsigned long gfn; + int ret; + + ret = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &val); + if (ret < 0 || val == 0) + return ret; + + priv->evtchn = val; + console_evtchn = val; + + ret = hvm_get_parameter(HVM_PARAM_CONSOLE_PFN, &val); + if (ret < 0) + return ret; + + if (!val) + return -EINVAL; + + gfn = val; + priv->intf = (struct xencons_interface *)(gfn << XEN_PAGE_SHIFT); + + return 0; +} + +static int xen_serial_pending(struct udevice *dev, bool input) +{ + struct xen_uart_priv *priv = dev_get_priv(dev); + struct xencons_interface *intf = priv->intf; + + if (!input || intf->in_cons == intf->in_prod) + return 0; + + return 1; +} + +static int xen_serial_getc(struct udevice *dev) +{ + struct xen_uart_priv *priv = dev_get_priv(dev); + struct xencons_interface *intf = priv->intf; + XENCONS_RING_IDX cons; + char c; + + while (intf->in_cons == intf->in_prod) + mb(); /* wait */ + + cons = intf->in_cons; + mb(); /* get pointers before reading ring */ + + c = intf->in[MASK_XENCONS_IDX(cons++, intf->in)]; + + mb(); /* read ring before consuming */ + intf->in_cons = cons; + + notify_remote_via_evtchn(priv->evtchn); + + return c; +} + +static int __write_console(struct udevice *dev, const char *data, int len) +{ + struct xen_uart_priv *priv = dev_get_priv(dev); + struct xencons_interface *intf = priv->intf; + XENCONS_RING_IDX cons, prod; + int sent = 0; + + cons = intf->out_cons; + prod = intf->out_prod; + mb(); /* Update pointer */ + + WARN_ON((prod - cons) > sizeof(intf->out)); + + while ((sent < len) && ((prod - cons) < sizeof(intf->out))) + intf->out[MASK_XENCONS_IDX(prod++, intf->out)] = data[sent++]; + + mb(); /* Update data before pointer */ + intf->out_prod = prod; + + if (sent) + notify_remote_via_evtchn(priv->evtchn); + + return sent; +} + +static int write_console(struct udevice *dev, const char *data, int len) +{ + /* + * Make sure the whole buffer is emitted, polling if + * necessary. We don't ever want to rely on the hvc daemon + * because the most interesting console output is when the + * kernel is crippled. + */ + while (len) { + int sent = __write_console(dev, data, len); + + data += sent; + len -= sent; + + if (unlikely(len)) + HYPERVISOR_sched_op(SCHEDOP_yield, NULL); + } + + return 0; +} + +static int xen_serial_putc(struct udevice *dev, const char ch) +{ + write_console(dev, &ch, 1); + + return 0; +} + +static const struct dm_serial_ops xen_serial_ops = { + .putc = xen_serial_putc, + .getc = xen_serial_getc, + .pending = xen_serial_pending, +}; + +#if CONFIG_IS_ENABLED(OF_CONTROL) +static const struct udevice_id xen_serial_ids[] = { + { .compatible = "xen,xen" }, + { } +}; +#endif + +U_BOOT_DRIVER(serial_xen) = { + .name = "serial_xen", + .id = UCLASS_SERIAL, +#if CONFIG_IS_ENABLED(OF_CONTROL) + .of_match = xen_serial_ids, +#endif + .priv_auto_alloc_size = sizeof(struct xen_uart_priv), + .probe = xen_serial_probe, + .ops = &xen_serial_ops, +#if !CONFIG_IS_ENABLED(OF_CONTROL) + .flags = DM_FLAG_PRE_RELOC, +#endif +}; + |