Re: [Qemu-devel] [Patch v1 2/8] stm32f205_USART: Add the stm32f205 USART Controller

[Peter Crosthwaite]

On Sun, Sep 14, 2014 at 6:18 PM, Alistair Francis <address@hidden> wrote:
> This patch adds the stm32f205 USART controller
> (UART also uses the same controller).
>
> Signed-off-by: Alistair Francis <address@hidden>
> ---
> Changes from RFC:
>  - Small changes thanks to Peter C
>  - USART now implements QEMU blocking functions
>  - Split the config settings to device level
>
>  default-configs/arm-softmmu.mak   |   1 +
>  hw/char/Makefile.objs             |   1 +
>  hw/char/stm32f205_usart.c         | 213 
> ++++++++++++++++++++++++++++++++++++++
>  include/hw/char/stm32f205_usart.h |  67 ++++++++++++
>  4 files changed, 282 insertions(+)
>  create mode 100644 hw/char/stm32f205_usart.c
>  create mode 100644 include/hw/char/stm32f205_usart.h
>
> diff --git a/default-configs/arm-softmmu.mak b/default-configs/arm-softmmu.mak
> index cf23b24..422dec0 100644
> --- a/default-configs/arm-softmmu.mak
> +++ b/default-configs/arm-softmmu.mak
> @@ -79,6 +79,7 @@ CONFIG_REALVIEW=y
>  CONFIG_ZAURUS=y
>  CONFIG_ZYNQ=y
>  CONFIG_STM32F205_TIMER=y
> +CONFIG_STM32F205_USART=y
>
>  CONFIG_VERSATILE_PCI=y
>  CONFIG_VERSATILE_I2C=y
> diff --git a/hw/char/Makefile.objs b/hw/char/Makefile.objs
> index 317385d..c7b3ce4 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-$(CONFIG_STM32F205_USART) += stm32f205_usart.o
>
>  common-obj-$(CONFIG_ETRAXFS) += etraxfs_ser.o
>  common-obj-$(CONFIG_ISA_DEBUG) += debugcon.o
> diff --git a/hw/char/stm32f205_usart.c b/hw/char/stm32f205_usart.c
> new file mode 100644
> index 0000000..1274e69
> --- /dev/null
> +++ b/hw/char/stm32f205_usart.c
> @@ -0,0 +1,213 @@
> +/*
> + * STM32F205 USART
> + *
> + * Copyright (c) 2014 Alistair Francis <address@hidden>
> + *
> + * 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/char/stm32f205_usart.h"
> +
> +#ifndef STM_USART_ERR_DEBUG
> +#define STM_USART_ERR_DEBUG 0
> +#endif
> +
> +#define DB_PRINT_L(lvl, fmt, args...) do { \
> +    if (STM_USART_ERR_DEBUG >= lvl) { \
> +        qemu_log("stm32f205_usart: %s:" fmt, __func__, ## args); \
> +    } \
> +} while (0);
> +
> +#define DB_PRINT(fmt, args...) DB_PRINT_L(1, fmt, ## args)
> +
> +static int stm32f205_usart_can_receive(void *opaque)
> +{
> +    STM32f205UsartState *s = opaque;
> +
> +    if (s->usart_cr1 & USART_CR1_UE && s->usart_cr1 & USART_CR1_RE &&

So this is still gating based on the master enable. I think these
first two terms in the && need to be dropped ...

> +        !(s->usart_sr & USART_SR_RXNE)) {
> +        return 1;
> +    }
> +
> +    return 0;
> +}
> +
> +static void stm32f205_usart_receive(void *opaque, const uint8_t *buf, int 
> size)
> +{
> +    STM32f205UsartState *s = opaque;
> +
> +    s->usart_dr = *buf;
> +

and here:

if (!s->usart_cr1 & USART_CR1_UE && s->usart_cr1 & USART_CR1_RE) {
   return; /* not enabled - drop chars */
}

This means the UART will drop chars when its disabled, which would be
consistent with real HW (there is no buffering when the sender sends
chars to a disabled UART).

> +    s->usart_sr |= USART_SR_RXNE;
> +
> +    if (s->usart_cr1 & USART_CR1_RXNEIE) {
> +        qemu_set_irq(s->irq, 1);
> +    }
> +
> +    DB_PRINT("Receiving: %c\n", s->usart_dr);
> +}
> +
> +static void stm32f205_usart_reset(DeviceState *dev)
> +{
> +    STM32f205UsartState *s = STM32F205_USART(dev);
> +
> +    s->usart_sr = 0x00C00000;

Just define a macro for this field and set it for self documentation.

> +    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 stm32f205_usart_read(void *opaque, hwaddr addr,
> +                                       unsigned int size)
> +{
> +    STM32f205UsartState *s = opaque;
> +    uint64_t retvalue;
> +
> +    DB_PRINT("Read 0x%"HWADDR_PRIx"\n", addr);
> +
> +    switch (addr) {
> +    case USART_SR:
> +        retvalue = s->usart_sr;
> +        s->usart_sr &= ~USART_SR_TC;
> +        if (s->chr) {
> +            qemu_chr_accept_input(s->chr);
> +        }
> +        return retvalue;
> +    case USART_DR:
> +        DB_PRINT("Value: 0x%x, %c\n", s->usart_dr, (char) s->usart_dr);

PRIx32 to match type of usart_dr.

> +        s->usart_sr |= USART_SR_TXE;
> +        s->usart_sr &= ~USART_SR_RXNE;
> +        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;
> +    default:
> +        qemu_log_mask(LOG_GUEST_ERROR,
> +                      "STM32F205_usart_read: Bad offset " \
> +                      "0x%"HWADDR_PRIx"\n", addr);
> +        return 0;
> +    }
> +
> +    return 0;
> +}
> +
> +static void stm32f205_usart_write(void *opaque, hwaddr addr,
> +                       uint64_t val64, unsigned int size)
> +{
> +    STM32f205UsartState *s = opaque;
> +    uint32_t value = val64;
> +    unsigned char ch;
> +
> +    DB_PRINT("Write 0x%x, 0x%"HWADDR_PRIx"\n", value, addr);
> +

PRIx64 for value.

Regards,
Peter