[5/8] xen/arm: Implement a virtual UART

This code is based on the previous vuart0 implementation. Unlike the latter,
it's intend to replace UART stolen by XEN to DOM0 via dtuart=... on its
command line.

It's useful when the kernel is compiled with early printk enabled or for a
single platform. Most of the time, the hardcoded code to handle the UART
will need 2 registers: status and data, the others registers can be
implemented as RAZ/WI.

Signed-off-by: Julien Grall <julien.grall@linaro.org>
---
 xen/arch/arm/Makefile        |    2 +-
 xen/arch/arm/domain.c        |   12 ++--
 xen/arch/arm/io.c            |    2 +-
 xen/arch/arm/io.h            |    2 +-
 xen/arch/arm/vpl011.c        |  152 ------------------------------------------
 xen/arch/arm/vpl011.h        |   35 ----------
 xen/arch/arm/vuart.c         |  150 +++++++++++++++++++++++++++++++++++++++++
 xen/arch/arm/vuart.h         |   35 ++++++++++
 xen/include/asm-arm/domain.h |   14 ++--
 9 files changed, 204 insertions(+), 200 deletions(-)
 delete mode 100644 xen/arch/arm/vpl011.c
 delete mode 100644 xen/arch/arm/vpl011.h
 create mode 100644 xen/arch/arm/vuart.c
 create mode 100644 xen/arch/arm/vuart.h

On Thu, 2013-07-25 at 17:59 +0100, Julien Grall wrote:
> This code is based on the previous vuart0 implementation. Unlike the latter,
> it's intend to replace UART stolen by XEN to DOM0 via dtuart=... on its
> command line.
> 
> It's useful when the kernel is compiled with early printk enabled or for a
> single platform. Most of the time, the hardcoded code to handle the UART
> will need 2 registers: status and data, the others registers can be
> implemented as RAZ/WI.
> 
> Signed-off-by: Julien Grall <julien.grall@linaro.org>
> ---
>  xen/arch/arm/Makefile        |    2 +-
>  xen/arch/arm/domain.c        |   12 ++--
>  xen/arch/arm/io.c            |    2 +-
>  xen/arch/arm/io.h            |    2 +-
>  xen/arch/arm/vpl011.c        |  152 ------------------------------------------
>  xen/arch/arm/vpl011.h        |   35 ----------
>  xen/arch/arm/vuart.c         |  150 +++++++++++++++++++++++++++++++++++++++++
>  xen/arch/arm/vuart.h         |   35 ++++++++++

Please can you use the -M option to format-patch/send-email so that the
rename is handled in a way which lets us review the actual diff between
the old and new files.

>  xen/include/asm-arm/domain.h |   14 ++--
>  9 files changed, 204 insertions(+), 200 deletions(-)
>  delete mode 100644 xen/arch/arm/vpl011.c
>  delete mode 100644 xen/arch/arm/vpl011.h
>  create mode 100644 xen/arch/arm/vuart.c
>  create mode 100644 xen/arch/arm/vuart.h
> 
> diff --git a/xen/arch/arm/Makefile b/xen/arch/arm/Makefile
> index 5ae5831..6e1208f 100644
> --- a/xen/arch/arm/Makefile
> +++ b/xen/arch/arm/Makefile
> @@ -27,7 +27,7 @@ obj-y += shutdown.o
>  obj-y += traps.o
>  obj-y += vgic.o
>  obj-y += vtimer.o
> -obj-y += vpl011.o
> +obj-y += vuart.o
>  obj-y += hvm.o
>  obj-y += device.o
>  
> diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
> index cfe0fbd..84b2f82 100644
> --- a/xen/arch/arm/domain.c
> +++ b/xen/arch/arm/domain.c
> @@ -32,7 +32,7 @@
>  
>  #include <asm/gic.h>
>  #include "vtimer.h"
> -#include "vpl011.h"
> +#include "vuart.h"
>  
>  DEFINE_PER_CPU(struct vcpu *, curr_vcpu);
>  
> @@ -518,8 +518,12 @@ int arch_domain_create(struct domain *d, unsigned int domcr_flags)
>      if ( (rc = vcpu_domain_init(d)) != 0 )
>          goto fail;
>  
> -    /* Domain 0 gets a real UART not an emulated one */
> -    if ( d->domain_id && (rc = domain_uart0_init(d)) != 0 )
> +    /*
> +     * Virtual UART is only used by linux early printk and decompress code.
> +     * Only use it for dom0 because the linux kernel may not support
> +     * multi-platform.
> +     */
> +    if ( (d->domain_id == 0) && (rc = domain_vuart_init(d)) )
>          goto fail;
>  
>      return 0;
> @@ -535,7 +539,7 @@ void arch_domain_destroy(struct domain *d)
>  {
>      p2m_teardown(d);
>      domain_vgic_free(d);
> -    domain_uart0_free(d);
> +    domain_vuart_free(d);
>      free_xenheap_page(d->shared_info);
>  }
>  
> diff --git a/xen/arch/arm/io.c b/xen/arch/arm/io.c
> index ad28c26..a6db00b 100644
> --- a/xen/arch/arm/io.c
> +++ b/xen/arch/arm/io.c
> @@ -25,7 +25,7 @@
>  static const struct mmio_handler *const mmio_handlers[] =
>  {
>      &vgic_distr_mmio_handler,
> -    &uart0_mmio_handler,
> +    &vuart_mmio_handler,
>  };
>  #define MMIO_HANDLER_NR ARRAY_SIZE(mmio_handlers)
>  
> diff --git a/xen/arch/arm/io.h b/xen/arch/arm/io.h
> index 661dce1..8d252c0 100644
> --- a/xen/arch/arm/io.h
> +++ b/xen/arch/arm/io.h
> @@ -41,7 +41,7 @@ struct mmio_handler {
>  };
>  
>  extern const struct mmio_handler vgic_distr_mmio_handler;
> -extern const struct mmio_handler uart0_mmio_handler;
> +extern const struct mmio_handler vuart_mmio_handler;
>  
>  extern int handle_mmio(mmio_info_t *info);
>  
> diff --git a/xen/arch/arm/vpl011.c b/xen/arch/arm/vpl011.c
> deleted file mode 100644
> index 13ba623..0000000
> --- a/xen/arch/arm/vpl011.c
> +++ /dev/null
> @@ -1,152 +0,0 @@
> -/*
> - * xen/arch/arm/vpl011.c
> - *
> - * ARM PL011 UART Emulator (DEBUG)
> - *
> - * Ian Campbell <ian.campbell@citrix.com>
> - * Copyright (c) 2012 Citrix Systems.
> - *
> - * 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.
> - */
> -
> -/*
> - * This is not intended to be a full emulation of a PL011
> - * device. Rather it is intended to provide a sufficient veneer of one
> - * that early code (such as Linux's boot time decompressor) which
> - * hardcodes output directly to such a device are able to make progress.
> - *
> - * This device is not intended to be enumerable or exposed to the OS
> - * (e.g. via Device Tree).
> - */
> -
> -#include <xen/config.h>
> -#include <xen/lib.h>
> -#include <xen/sched.h>
> -#include <xen/errno.h>
> -#include <xen/ctype.h>
> -
> -#include "io.h"
> -
> -#define UART0_START 0x1c090000
> -#define UART0_END   (UART0_START+65536)
> -
> -#define UARTDR 0x000
> -#define UARTFR 0x018
> -
> -int domain_uart0_init(struct domain *d)
> -{
> -    ASSERT( d->domain_id );
> -
> -    spin_lock_init(&d->arch.uart0.lock);
> -    d->arch.uart0.idx = 0;
> -
> -    d->arch.uart0.buf = xzalloc_array(char, VPL011_BUF_SIZE);
> -    if ( !d->arch.uart0.buf )
> -        return -ENOMEM;
> -
> -    return 0;
> -
> -}
> -
> -void domain_uart0_free(struct domain *d)
> -{
> -    xfree(d->arch.uart0.buf);
> -}
> -
> -static void uart0_print_char(char c)
> -{
> -    struct vpl011 *uart = &current->domain->arch.uart0;
> -
> -    /* Accept only printable characters, newline, and horizontal tab. */
> -    if ( !isprint(c) && (c != '\n') && (c != '\t') )
> -        return ;
> -
> -    spin_lock(&uart->lock);
> -    uart->buf[uart->idx++] = c;
> -    if ( (uart->idx == (VPL011_BUF_SIZE - 2)) || (c == '\n') )
> -    {
> -        if ( c != '\n' )
> -            uart->buf[uart->idx++] = '\n';
> -        uart->buf[uart->idx] = '\0';
> -        printk(XENLOG_G_DEBUG "DOM%u: %s",
> -               current->domain->domain_id, uart->buf);
> -        uart->idx = 0;
> -    }
> -    spin_unlock(&uart->lock);
> -}
> -
> -static int uart0_mmio_check(struct vcpu *v, paddr_t addr)
> -{
> -    struct domain *d = v->domain;
> -
> -    return d->domain_id != 0 && addr >= UART0_START && addr < UART0_END;
> -}
> -
> -static int uart0_mmio_read(struct vcpu *v, mmio_info_t *info)
> -{
> -    struct hsr_dabt dabt = info->dabt;
> -    struct cpu_user_regs *regs = guest_cpu_user_regs();
> -    register_t *r = select_user_reg(regs, dabt.reg);
> -    int offset = (int)(info->gpa - UART0_START);
> -
> -    switch ( offset )
> -    {
> -    case UARTDR:
> -        *r = 0;
> -        return 1;
> -    case UARTFR:
> -        *r = 0x87; /* All holding registers empty, ready to send etc */
> -        return 1;
> -    default:
> -        printk("VPL011: unhandled read r%d offset %#08x\n",
> -               dabt.reg, offset);
> -        domain_crash_synchronous();
> -    }
> -}
> -
> -static int uart0_mmio_write(struct vcpu *v, mmio_info_t *info)
> -{
> -    struct hsr_dabt dabt = info->dabt;
> -    struct cpu_user_regs *regs = guest_cpu_user_regs();
> -    register_t *r = select_user_reg(regs, dabt.reg);
> -    int offset = (int)(info->gpa - UART0_START);
> -
> -    switch ( offset )
> -    {
> -    case UARTDR:
> -        /* ignore any status bits */
> -        uart0_print_char((int)((*r) & 0xFF));
> -        return 1;
> -    case UARTFR:
> -        /* Silently ignore */
> -        return 1;
> -    default:
> -        printk("VPL011: unhandled write r%d=%"PRIregister" offset %#08x\n",
> -               dabt.reg, *r, offset);
> -        domain_crash_synchronous();
> -    }
> -}
> -
> -const struct mmio_handler uart0_mmio_handler = {
> -    .check_handler = uart0_mmio_check,
> -    .read_handler  = uart0_mmio_read,
> -    .write_handler = uart0_mmio_write,
> -};
> -
> -/*
> - * Local variables:
> - * mode: C
> - * c-file-style: "BSD"
> - * c-basic-offset: 4
> - * indent-tabs-mode: nil
> - * End:
> - */
> -
> diff --git a/xen/arch/arm/vpl011.h b/xen/arch/arm/vpl011.h
> deleted file mode 100644
> index f0d0a82..0000000
> --- a/xen/arch/arm/vpl011.h
> +++ /dev/null
> @@ -1,35 +0,0 @@
> -/*
> - * xen/arch/arm/vpl011.h
> - *
> - * ARM PL011 Emulation Support
> - *
> - * Ian Campbell <ian.campbell@citrix.com>
> - * Copyright (c) 2012 Citrix Systems.
> - *
> - * 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.
> - */
> -
> -#ifndef __ARCH_ARM_VPL011_H__
> -#define __ARCH_ARM_VPL011_H__
> -
> -extern int domain_uart0_init(struct domain *d);
> -extern void domain_uart0_free(struct domain *d);
> -
> -#endif
> -
> -/*
> - * Local variables:
> - * mode: C
> - * c-file-style: "BSD"
> - * c-basic-offset: 4
> - * indent-tabs-mode: nil
> - * End:
> - */
> diff --git a/xen/arch/arm/vuart.c b/xen/arch/arm/vuart.c
> new file mode 100644
> index 0000000..5c3a84c
> --- /dev/null
> +++ b/xen/arch/arm/vuart.c
> @@ -0,0 +1,150 @@
> +/*
> + * xen/arch/arm/vuart.c
> + *
> + * Virtual UART Emulator.
> + *
> + * The emulator uses the information from dtuart. It will expose a basic
> + * UART which will allow the guest to log with an hardcode UART (early printk +
> + * decompressor).
> + *
> + * Julien Grall <julien.grall@linaro.org>
> + * Ian Campbell <ian.campbell@citrix.com>
> + * Copyright (c) 2012 Citrix Systems.
> + *
> + * 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.
> + */
> +
> +/*
> + * This is not intended to be a full emulation of a PL011
> + * device. Rather it is intended to provide a sufficient veneer of one
> + * that early code (such as Linux's boot time decompressor) which
> + * hardcodes output directly to such a device are able to make progress.
> + *
> + * This device is not intended to be enumerable or exposed to the OS
> + * (e.g. via Device Tree).
> + */
> +
> +#include <xen/config.h>
> +#include <xen/lib.h>
> +#include <xen/sched.h>
> +#include <xen/errno.h>
> +#include <xen/ctype.h>
> +#include <xen/serial.h>
> +
> +#include "vuart.h"
> +#include "io.h"
> +
> +#define domain_has_vuart(d) ((d)->arch.vuart.info != NULL)
> +
> +int domain_vuart_init(struct domain *d)
> +{
> +    ASSERT( !d->domain_id );
> +
> +    d->arch.vuart.info = serial_info(SERHND_DTUART);
> +    if ( !d->arch.vuart.info )
> +        return 0;
> +
> +    spin_lock_init(&d->arch.vuart.lock);
> +    d->arch.vuart.idx = 0;
> +
> +    d->arch.vuart.buf = xzalloc_array(char, VUART_BUF_SIZE);
> +    if ( !d->arch.vuart.buf )
> +        return -ENOMEM;
> +
> +    return 0;
> +}
> +
> +void domain_vuart_free(struct domain *d)
> +{
> +    if ( !domain_has_vuart(d) )
> +        return;
> +
> +    xfree(d->arch.vuart.buf);
> +}
> +
> +static void vuart_print_char(char c)
> +{
> +    struct vuart *uart = &current->domain->arch.vuart;
> +
> +    /* Accept only printable characters, newline, and horizontal tab. */
> +    if ( !isprint(c) && (c != '\n') && (c != '\t') )
> +        return ;
> +
> +    spin_lock(&uart->lock);
> +    uart->buf[uart->idx++] = c;
> +    if ( (uart->idx == (VUART_BUF_SIZE - 2)) || (c == '\n') )
> +    {
> +        if ( c != '\n' )
> +            uart->buf[uart->idx++] = '\n';
> +        uart->buf[uart->idx] = '\0';
> +        printk(XENLOG_G_DEBUG "DOM%u: %s",
> +               current->domain->domain_id, uart->buf);
> +        uart->idx = 0;
> +    }
> +    spin_unlock(&uart->lock);
> +}
> +
> +static int vuart_mmio_check(struct vcpu *v, paddr_t addr)
> +{
> +    const struct serial_info *info = v->domain->arch.vuart.info;
> +
> +    return (domain_has_vuart(v->domain) && addr >= info->base_addr &&
> +            addr <= (info->base_addr + info->size));
> +}
> +
> +static int vuart_mmio_read(struct vcpu *v, mmio_info_t *info)
> +{
> +    struct domain *d = v->domain;
> +    struct hsr_dabt dabt = info->dabt;
> +    struct cpu_user_regs *regs = guest_cpu_user_regs();
> +    register_t *r = select_user_reg(regs, dabt.reg);
> +    paddr_t offset = info->gpa - d->arch.vuart.info->base_addr;
> +
> +    /* By default zeroed the register */
> +    *r = 0;
> +
> +    if ( offset == d->arch.vuart.info->status_off )
> +        /* All holding registers empty, ready to send etc */
> +        *r = d->arch.vuart.info->status;
> +
> +    return 1;
> +}
> +
> +static int vuart_mmio_write(struct vcpu *v, mmio_info_t *info)
> +{
> +    struct domain *d = v->domain;
> +    struct hsr_dabt dabt = info->dabt;
> +    struct cpu_user_regs *regs = guest_cpu_user_regs();
> +    register_t *r = select_user_reg(regs, dabt.reg);
> +    paddr_t offset = (int)(info->gpa - d->arch.vuart.info->base_addr);
> +
> +    if ( offset == d->arch.vuart.info->data_off )
> +        /* ignore any status bits */
> +        vuart_print_char((int)((*r) & 0xFF));
> +
> +    return 1;
> +}
> +
> +const struct mmio_handler vuart_mmio_handler = {
> +    .check_handler = vuart_mmio_check,
> +    .read_handler  = vuart_mmio_read,
> +    .write_handler = vuart_mmio_write,
> +};
> +
> +/*
> + * Local variables:
> + * mode: C
> + * c-file-style: "BSD"
> + * c-basic-offset: 4
> + * indent-tabs-mode: nil
> + * End:
> + */
> +
> diff --git a/xen/arch/arm/vuart.h b/xen/arch/arm/vuart.h
> new file mode 100644
> index 0000000..9445e50
> --- /dev/null
> +++ b/xen/arch/arm/vuart.h
> @@ -0,0 +1,35 @@
> +/* 
> + * xen/arch/arm/vuart.h
> + *
> + * Virtual UART Emulation Support
> + *
> + * Ian Campbell <ian.campbell@citrix.com>
> + * Copyright (c) 2012 Citrix Systems.
> + *
> + * 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.
> + */
> +
> +#ifndef __ARCH_ARM_VUART_H__
> +#define __ARCH_ARM_VUART_H__
> +
> +int domain_vuart_init(struct domain *d);
> +void domain_vuart_free(struct domain *d);
> +
> +#endif /* __ARCH_ARM_VUART_H__ */
> +
> +/*
> + * Local variables:
> + * mode: C
> + * c-file-style: "BSD"
> + * c-basic-offset: 4
> + * indent-tabs-mode: nil
> + * End:
> + */
> diff --git a/xen/include/asm-arm/domain.h b/xen/include/asm-arm/domain.h
> index 19bbe8a..216ce0b 100644
> --- a/xen/include/asm-arm/domain.h
> +++ b/xen/include/asm-arm/domain.h
> @@ -9,6 +9,7 @@
>  #include <asm/vfp.h>
>  #include <public/hvm/params.h>
>  #include <asm/atomic.h>
> +#include <xen/serial.h>
>  
>  /* Represents state corresponding to a block of 32 interrupts */
>  struct vgic_irq_rank {
> @@ -104,12 +105,13 @@ struct arch_domain
>          paddr_t cbase; /* CPU base address */
>      } vgic;
>  
> -    struct vpl011 {
> -#define VPL011_BUF_SIZE 128
> -        char                  *buf;
> -        int                    idx;
> -        spinlock_t             lock;
> -    } uart0;
> +    struct vuart {
> +#define VUART_BUF_SIZE 128
> +        char                        *buf;
> +        int                         idx;
> +        const struct serial_info    *info;
> +        spinlock_t                  lock;
> +    } vuart;
>  
>  }  __cacheline_aligned;
>