Re: [Qemu-devel] [PATCH v1 1/5] Netduino_USART: Add the Netduino Plus 2 USART Controller

[Peter Crosthwaite <peter.crosthwaite@xilinx.com>]

On Sun, Aug 24, 2014 at 10:13 AM, Alistair Francis <alistair23@gmail.com> wrote:
> This patch adds the Netduino Plus 2 USART controller
> (UART also uses the same controller).
>
> It can be used for reading and writing to the guest.
>

Do you just mean doing IO with the system?

> Signed-off-by: Alistair Francis <alistair23@gmail.com>
> ---
>  default-configs/arm-softmmu.mak |   1 +
>  hw/char/Makefile.objs           |   1 +
>  hw/char/netduino_usart.c        | 252 ++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 254 insertions(+)
>  create mode 100644 hw/char/netduino_usart.c
>
> diff --git a/default-configs/arm-softmmu.mak b/default-configs/arm-softmmu.mak
> index f3513fa..46471ad 100644
> --- a/default-configs/arm-softmmu.mak
> +++ b/default-configs/arm-softmmu.mak
> @@ -78,6 +78,7 @@ CONFIG_NSERIES=y
>  CONFIG_REALVIEW=y
>  CONFIG_ZAURUS=y
>  CONFIG_ZYNQ=y
> +CONFIG_NETDUINOP2=y
>
>  CONFIG_VERSATILE_PCI=y
>  CONFIG_VERSATILE_I2C=y
> diff --git a/hw/char/Makefile.objs b/hw/char/Makefile.objs
> index 317385d..c03aa98 100644
> --- a/hw/char/Makefile.objs
> +++ b/hw/char/Makefile.objs
> @@ -15,6 +15,7 @@ obj-$(CONFIG_OMAP) += omap_uart.o
>  obj-$(CONFIG_SH4) += sh_serial.o
>  obj-$(CONFIG_PSERIES) += spapr_vty.o
>  obj-$(CONFIG_DIGIC) += digic-uart.o
> +obj-$(CONFIG_NETDUINOP2) += netduino_usart.o
>
>  common-obj-$(CONFIG_ETRAXFS) += etraxfs_ser.o
>  common-obj-$(CONFIG_ISA_DEBUG) += debugcon.o
> diff --git a/hw/char/netduino_usart.c b/hw/char/netduino_usart.c
> new file mode 100644
> index 0000000..437af2b
> --- /dev/null
> +++ b/hw/char/netduino_usart.c
> @@ -0,0 +1,252 @@
> +/*
> + * Netduino Plus 2 USART
> + *

I thing the UART IP is really part of the ST Microcontroller, and
should be named as such. Do ST give this controller a meaningful name
in their documentation? Looking at the schematic for Netduino it looks
like there is very little board level IP. All the sysbus IP is local
to the microcontroller. I think the name "netduino" should probably
only be limited to the board level.

> + * Copyright (c) 2014 Alistair Francis <alistair@alistair23.me>
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a copy
> + * of this software and associated documentation files (the "Software"), to deal
> + * in the Software without restriction, including without limitation the rights
> + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
> + * copies of the Software, and to permit persons to whom the Software is
> + * furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice shall be included in
> + * all copies or substantial portions of the Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
> + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
> + * THE SOFTWARE.
> + */
> +
> +#include "hw/sysbus.h"
> +#include "sysemu/char.h"
> +#include "hw/hw.h"
> +
> +/* #define DEBUG_NETUSART */

Don't worry about commented out //#defines

> +
> +#ifdef DEBUG_NETUSART
> +#define DPRINTF(fmt, ...) \

You should change this to a always-compiled print using a regular if.
Check hw/dma/pl330.c

> +do { printf("netduino_usart: " fmt , ## __VA_ARGS__); } while (0)

Multiple lines to keep formatting standard even within #define. use \ as needed.

Use qemu_log instead of printf. (pl330 fails at this too).

> +#else
> +#define DPRINTF(fmt, ...) do {} while (0)
> +#endif
> +
> +#define USART_SR   0x00
> +#define USART_DR   0x04
> +#define USART_BRR  0x08
> +#define USART_CR1  0x0C
> +#define USART_CR2  0x10
> +#define USART_CR3  0x14
> +#define USART_GTPR 0x18
> +
> +#define USART_SR_TXE  (1 << 7)
> +#define USART_SR_TC   (1 << 6)
> +#define USART_SR_RXNE (1 << 5)
> +
> +#define USART_CR1_UE  (1 << 13)
> +#define USART_CR1_RXNEIE  (1 << 5)
> +#define USART_CR1_TE  (1 << 3)
> +
> +#define TYPE_NETDUINO_USART "netduino_usart"

Change "_" to "-" in QOM typename.

> +#define NETDUINO_USART(obj) \
> +    OBJECT_CHECK(struct net_usart, (obj), TYPE_NETDUINO_USART)
> +
> +struct net_usart {

CamelCase in typename. Use a typedef to avoid the repeated struct Foo
all throughout.

> +    SysBusDevice parent_obj;
> +
> +    MemoryRegion mmio;
> +
> +    uint32_t usart_sr;
> +    uint32_t usart_dr;
> +    uint32_t usart_brr;
> +    uint32_t usart_cr1;
> +    uint32_t usart_cr2;
> +    uint32_t usart_cr3;
> +    uint32_t usart_gtpr;
> +
> +    CharDriverState *chr;
> +    qemu_irq irq;
> +};

The struct, QOM typename and register defines should go in a device
specific header. Check include/hw/char/digic_uart.h for an example.

> +
> +static int usart_can_receive(void *opaque)
> +{
> +    struct net_usart *s = opaque;
> +
> +    if (s->usart_cr1 & USART_CR1_UE && s->usart_cr1 & USART_CR1_TE) {
> +        return 1;
> +    }
> +
> +    return 0;
> +}
> +
> +static void usart_receive(void *opaque, const uint8_t *buf, int size)
> +{
> +    struct net_usart *s = opaque;
> +    int i, num;
> +
> +    num = size > 8 ? 8 : size;

MAX macro.

> +    s->usart_dr = 0;
> +
> +    for (i = 0; i < num; i++) {
> +        s->usart_dr |= (buf[i] << i);
> +    }

This seems strange. dr is an oring of multiple rxed characters? Is RX
information lost here when size > 1?

> +
> +    s->usart_sr |= USART_SR_RXNE;
> +
> +    if (s->usart_cr1 & USART_CR1_RXNEIE) {
> +        qemu_set_irq(s->irq, 1);
> +    }
> +
> +    DPRINTF("Inputting: %c\n", s->usart_dr);

"receiving"

> +}
> +
> +static void usart_reset(DeviceState *dev)
> +{
> +    struct net_usart *s = NETDUINO_USART(dev);
> +
> +    s->usart_sr = 0x00C00000;
> +    s->usart_dr = 0x00000000;
> +    s->usart_brr = 0x00000000;
> +    s->usart_cr1 = 0x00000000;
> +    s->usart_cr2 = 0x00000000;
> +    s->usart_cr3 = 0x00000000;
> +    s->usart_gtpr = 0x00000000;
> +}
> +
> +static uint64_t netduino_usart_read(void *opaque, hwaddr addr,
> +                                    unsigned int size)
> +{
> +    struct net_usart *s = opaque;
> +    uint64_t retvalue;
> +
> +    DPRINTF("Read 0x%x\n", (uint) addr);
> +
> +    switch (addr) {
> +    case USART_SR:
> +        retvalue = s->usart_sr;
> +        s->usart_sr &= (USART_SR_TC ^ 0xFFFF);
> +        return retvalue;
> +    case USART_DR:
> +        DPRINTF("Value: %x, %c\n", s->usart_dr, s->usart_dr);

PRIx32 instead of %x. Cast the %c version.

> +        s->usart_sr |= USART_SR_TXE;
> +        return s->usart_dr & 0x3FF;
> +    case USART_BRR:
> +        return s->usart_brr;
> +    case USART_CR1:
> +        return s->usart_cr1;
> +    case USART_CR2:
> +        return s->usart_cr2;
> +    case USART_CR3:
> +        return s->usart_cr3;
> +    case USART_GTPR:
> +        return s->usart_gtpr;

If you make your registers an array, you can index the with the offset
and remove the repeated s->foo return logic. You can also use a single
memset to do all the 0 resets.

> +    default:
> +        qemu_log_mask(LOG_GUEST_ERROR,
> +                      "net_usart_read: Bad offset %x\n", (int)addr);
> +        return 0;
> +    }
> +
> +    return 0;
> +}
> +
> +static void netduino_usart_write(void *opaque, hwaddr addr,
> +                       uint64_t val64, unsigned int size)
> +{
> +    struct net_usart *s = opaque;
> +    uint32_t value = (uint32_t) val64;
> +    unsigned char ch;
> +
> +    DPRINTF("Write 0x%x, 0x%x\n", value, (uint) addr);
> +
> +    switch (addr) {
> +    case USART_SR:
> +        if (value <= 0x3FF) {
> +            s->usart_sr = value;
> +        } else {
> +            s->usart_sr &= value;
> +        }
> +        return;
> +    case USART_DR:
> +        if (value < 0xF000) {
> +            ch = value;
> +            if (s->chr) {
> +                qemu_chr_fe_write(s->chr, &ch, 1);
> +            }
> +            s->usart_sr |= USART_SR_TC;
> +        }
> +        return;
> +    case USART_BRR:
> +        s->usart_brr = value;
> +        return;
> +    case USART_CR1:
> +        s->usart_cr1 = value;
> +        return;
> +    case USART_CR2:
> +        s->usart_cr2 = value;
> +        return;
> +    case USART_CR3:
> +        s->usart_cr3 = value;
> +        return;
> +    case USART_GTPR:
> +        s->usart_gtpr = value;
> +        return;
> +    default:
> +        qemu_log_mask(LOG_GUEST_ERROR,
> +                      "net_usart_write: Bad offset %x\n", (int)addr);
> +    }
> +}
> +
> +static const MemoryRegionOps netduino_usart_ops = {
> +    .read = netduino_usart_read,
> +    .write = netduino_usart_write,
> +    .endianness = DEVICE_NATIVE_ENDIAN,
> +};
> +
> +static int netduino_usart_init(SysBusDevice *sbd)
> +{
> +    DeviceState *dev = DEVICE(sbd);
> +    struct net_usart *s = NETDUINO_USART(dev);
> +
> +    sysbus_init_irq(sbd, &s->irq);
> +
> +    memory_region_init_io(&s->mmio, OBJECT(s), &netduino_usart_ops, s,
> +                          TYPE_NETDUINO_USART, 0x2000);
> +    sysbus_init_mmio(sbd, &s->mmio);
> +
> +    s->chr = qemu_char_get_next_serial();
> +
> +    if (s->chr) {
> +        qemu_chr_add_handlers(s->chr, usart_can_receive, usart_receive,
> +                              NULL, s);
> +    }
> +
> +    return 0;
> +}
> +
> +static void netduino_usart_class_init(ObjectClass *klass, void *data)
> +{
> +    DeviceClass *dc = DEVICE_CLASS(klass);
> +    SysBusDeviceClass *k = SYS_BUS_DEVICE_CLASS(klass);
> +
> +    k->init = netduino_usart_init;

Use of Sysbus::init is deprecated, please use device init and realize instead.

> +    dc->props = NULL;

Unneeded.

Some comments also apply to the following patches.

Regards,
Peter

> +    dc->reset = usart_reset;
> +}
> +
> +static const TypeInfo netduino_usart_info = {
> +    .name          = TYPE_NETDUINO_USART,
> +    .parent        = TYPE_SYS_BUS_DEVICE,
> +    .instance_size = sizeof(struct net_usart),
> +    .class_init    = netduino_usart_class_init,
> +};
> +
> +static void netduino_usart_register_types(void)
> +{
> +    type_register_static(&netduino_usart_info);
> +}
> +
> +type_init(netduino_usart_register_types)
> --
> 1.9.1
>
>