Re: [RFC PATCH 6/6] dp8393x: Rewrite dp8393x_get() / dp8393x_put()

[Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>]

On 03/07/2021 15:19, Philippe Mathieu-Daudé wrote:

> Instead of accessing N registers via a single address_space API
> call using a temporary buffer (stored in the device state) and
> updating each register, move the address_space call in the
> register put/get. The load/store and word size checks are moved
> to put/get too. This simplifies a bit, making the code easier
> to read.
> 
> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> ---
>   hw/net/dp8393x.c | 157 ++++++++++++++++++-----------------------------
>   1 file changed, 60 insertions(+), 97 deletions(-)
> 
> diff --git a/hw/net/dp8393x.c b/hw/net/dp8393x.c
> index bbe241ef9db..db9cfd786f5 100644
> --- a/hw/net/dp8393x.c
> +++ b/hw/net/dp8393x.c
> @@ -162,7 +162,6 @@ struct dp8393xState {
>   
>       /* Temporaries */
>       uint8_t tx_buffer[0x10000];
> -    uint16_t data[12];
>       int loopback_packet;
>   
>       /* Memory access */
> @@ -219,34 +218,48 @@ static uint32_t dp8393x_wt(dp8393xState *s)
>       return s->regs[SONIC_WT1] << 16 | s->regs[SONIC_WT0];
>   }
>   
> -static uint16_t dp8393x_get(dp8393xState *s, int width, int offset)
> +static uint16_t dp8393x_get(dp8393xState *s, hwaddr addr, unsigned ofs16)
>   {
> +    const MemTxAttrs attrs = MEMTXATTRS_UNSPECIFIED;
>       uint16_t val;
>   
> -    if (s->big_endian) {
> -        val = be16_to_cpu(s->data[offset * width + width - 1]);
> +    if (s->regs[SONIC_DCR] & SONIC_DCR_DW) {
> +        addr += 2 * ofs16;
> +        if (s->big_endian) {
> +            val = address_space_ldl_be(&s->as, addr, attrs, NULL);
> +        } else {
> +            val = address_space_ldl_le(&s->as, addr, attrs, NULL);
> +        }
>       } else {
> -        val = le16_to_cpu(s->data[offset * width]);
> +        addr += 1 * ofs16;
> +        if (s->big_endian) {
> +            val = address_space_lduw_be(&s->as, addr, attrs, NULL);
> +        } else {
> +            val = address_space_lduw_le(&s->as, addr, attrs, NULL);
> +        }
>       }
> +
>       return val;
>   }
>   
> -static void dp8393x_put(dp8393xState *s, int width, int offset,
> -                        uint16_t val)
> +static void dp8393x_put(dp8393xState *s,
> +                        hwaddr addr, unsigned ofs16, uint16_t val)
>   {
> -    if (s->big_endian) {
> -        if (width == 2) {
> -            s->data[offset * 2] = 0;
> -            s->data[offset * 2 + 1] = cpu_to_be16(val);
> +    const MemTxAttrs attrs = MEMTXATTRS_UNSPECIFIED;
> +
> +    if (s->regs[SONIC_DCR] & SONIC_DCR_DW) {
> +        addr += 2 * ofs16;
> +        if (s->big_endian) {
> +            address_space_stl_be(&s->as, addr, val, attrs, NULL);
>           } else {
> -            s->data[offset] = cpu_to_be16(val);
> +            address_space_stl_le(&s->as, addr, val, attrs, NULL);
>           }
>       } else {
> -        if (width == 2) {
> -            s->data[offset * 2] = cpu_to_le16(val);
> -            s->data[offset * 2 + 1] = 0;
> +        addr += 1 * ofs16;
> +        if (s->big_endian) {
> +            address_space_stw_be(&s->as, addr, val, attrs, NULL);
>           } else {
> -            s->data[offset] = cpu_to_le16(val);
> +            address_space_stw_le(&s->as, addr, val, attrs, NULL);
>           }
>       }
>   }
> @@ -277,12 +290,10 @@ static void dp8393x_do_load_cam(dp8393xState *s)
>   
>       while (s->regs[SONIC_CDC] & 0x1f) {
>           /* Fill current entry */
> -        address_space_read(&s->as, dp8393x_cdp(s),
> -                           MEMTXATTRS_UNSPECIFIED, s->data, size);
> -        index = dp8393x_get(s, width, 0) & 0xf;
> -        s->cam[index][0] = dp8393x_get(s, width, 1);
> -        s->cam[index][1] = dp8393x_get(s, width, 2);
> -        s->cam[index][2] = dp8393x_get(s, width, 3);
> +        index = dp8393x_get(s, dp8393x_cdp(s), 0) & 0xf;
> +        s->cam[index][0] = dp8393x_get(s, dp8393x_cdp(s), 1);
> +        s->cam[index][1] = dp8393x_get(s, dp8393x_cdp(s), 2);
> +        s->cam[index][2] = dp8393x_get(s, dp8393x_cdp(s), 3);
>           trace_dp8393x_load_cam(index,
>                                  s->cam[index][0] >> 8, s->cam[index][0] & 0xff,
>                                  s->cam[index][1] >> 8, s->cam[index][1] & 0xff,
> @@ -293,9 +304,7 @@ static void dp8393x_do_load_cam(dp8393xState *s)
>       }
>   
>       /* Read CAM enable */
> -    address_space_read(&s->as, dp8393x_cdp(s),
> -                       MEMTXATTRS_UNSPECIFIED, s->data, size);
> -    s->regs[SONIC_CE] = dp8393x_get(s, width, 0);
> +    s->regs[SONIC_CE] = dp8393x_get(s, dp8393x_cdp(s), 0);
>       trace_dp8393x_load_cam_done(s->regs[SONIC_CE]);
>   
>       /* Done */
> @@ -311,14 +320,12 @@ static void dp8393x_do_read_rra(dp8393xState *s)
>       /* Read memory */
>       width = (s->regs[SONIC_DCR] & SONIC_DCR_DW) ? 2 : 1;
>       size = sizeof(uint16_t) * 4 * width;
> -    address_space_read(&s->as, dp8393x_rrp(s),
> -                       MEMTXATTRS_UNSPECIFIED, s->data, size);
>   
>       /* Update SONIC registers */
> -    s->regs[SONIC_CRBA0] = dp8393x_get(s, width, 0);
> -    s->regs[SONIC_CRBA1] = dp8393x_get(s, width, 1);
> -    s->regs[SONIC_RBWC0] = dp8393x_get(s, width, 2);
> -    s->regs[SONIC_RBWC1] = dp8393x_get(s, width, 3);
> +    s->regs[SONIC_CRBA0] = dp8393x_get(s, dp8393x_rrp(s), 0);
> +    s->regs[SONIC_CRBA1] = dp8393x_get(s, dp8393x_rrp(s), 1);
> +    s->regs[SONIC_RBWC0] = dp8393x_get(s, dp8393x_rrp(s), 2);
> +    s->regs[SONIC_RBWC1] = dp8393x_get(s, dp8393x_rrp(s), 3);
>       trace_dp8393x_read_rra_regs(s->regs[SONIC_CRBA0], s->regs[SONIC_CRBA1],
>                                   s->regs[SONIC_RBWC0], s->regs[SONIC_RBWC1]);
>   
> @@ -414,28 +421,22 @@ static void dp8393x_do_receiver_disable(dp8393xState *s)
>   static void dp8393x_do_transmit_packets(dp8393xState *s)
>   {
>       NetClientState *nc = qemu_get_queue(s->nic);
> -    int width, size;
>       int tx_len, len;
>       uint16_t i;
>   
> -    width = (s->regs[SONIC_DCR] & SONIC_DCR_DW) ? 2 : 1;
> -
>       while (1) {
>           /* Read memory */
> -        size = sizeof(uint16_t) * 6 * width;
>           s->regs[SONIC_TTDA] = s->regs[SONIC_CTDA];
>           trace_dp8393x_transmit_packet(dp8393x_ttda(s));
> -        address_space_read(&s->as, dp8393x_ttda(s) + sizeof(uint16_t) * width,
> -                           MEMTXATTRS_UNSPECIFIED, s->data, size);
>           tx_len = 0;
>   
>           /* Update registers */
> -        s->regs[SONIC_TCR] = dp8393x_get(s, width, 0) & 0xf000;
> -        s->regs[SONIC_TPS] = dp8393x_get(s, width, 1);
> -        s->regs[SONIC_TFC] = dp8393x_get(s, width, 2);
> -        s->regs[SONIC_TSA0] = dp8393x_get(s, width, 3);
> -        s->regs[SONIC_TSA1] = dp8393x_get(s, width, 4);
> -        s->regs[SONIC_TFS] = dp8393x_get(s, width, 5);
> +        s->regs[SONIC_TCR] = dp8393x_get(s, dp8393x_ttda(s), 0) & 0xf000;
> +        s->regs[SONIC_TPS] = dp8393x_get(s, dp8393x_ttda(s), 1);
> +        s->regs[SONIC_TFC] = dp8393x_get(s, dp8393x_ttda(s), 2);
> +        s->regs[SONIC_TSA0] = dp8393x_get(s, dp8393x_ttda(s), 3);
> +        s->regs[SONIC_TSA1] = dp8393x_get(s, dp8393x_ttda(s), 4);
> +        s->regs[SONIC_TFS] = dp8393x_get(s, dp8393x_ttda(s), 5);
>   
>           /* Handle programmable interrupt */
>           if (s->regs[SONIC_TCR] & SONIC_TCR_PINT) {
> @@ -457,15 +458,9 @@ static void dp8393x_do_transmit_packets(dp8393xState *s)
>               i++;
>               if (i != s->regs[SONIC_TFC]) {
>                   /* Read next fragment details */
> -                size = sizeof(uint16_t) * 3 * width;
> -                address_space_read(&s->as,
> -                                   dp8393x_ttda(s)
> -                                   + sizeof(uint16_t) * width * (4 + 3 * i),
> -                                   MEMTXATTRS_UNSPECIFIED, s->data,
> -                                   size);
> -                s->regs[SONIC_TSA0] = dp8393x_get(s, width, 0);
> -                s->regs[SONIC_TSA1] = dp8393x_get(s, width, 1);
> -                s->regs[SONIC_TFS] = dp8393x_get(s, width, 2);
> +                s->regs[SONIC_TSA0] = dp8393x_get(s, dp8393x_ttda(s), 0);
> +                s->regs[SONIC_TSA1] = dp8393x_get(s, dp8393x_ttda(s), 1);
> +                s->regs[SONIC_TFS] = dp8393x_get(s, dp8393x_ttda(s), 2);
>               }
>           }
>   
> @@ -498,22 +493,12 @@ static void dp8393x_do_transmit_packets(dp8393xState *s)
>           s->regs[SONIC_TCR] |= SONIC_TCR_PTX;
>   
>           /* Write status */
> -        dp8393x_put(s, width, 0,
> -                    s->regs[SONIC_TCR] & 0x0fff); /* status */
> -        size = sizeof(uint16_t) * width;
> -        address_space_write(&s->as, dp8393x_ttda(s),
> -                            MEMTXATTRS_UNSPECIFIED, s->data, size);
> +        dp8393x_put(s, dp8393x_ttda(s), 0, s->regs[SONIC_TCR] & 0x0fff);
>   
>           if (!(s->regs[SONIC_CR] & SONIC_CR_HTX)) {
>               /* Read footer of packet */
> -            size = sizeof(uint16_t) * width;
> -            address_space_read(&s->as,
> -                               dp8393x_ttda(s)
> -                               + sizeof(uint16_t) * width
> -                                 * (4 + 3 * s->regs[SONIC_TFC]),
> -                               MEMTXATTRS_UNSPECIFIED, s->data,
> -                               size);
> -            s->regs[SONIC_CTDA] = dp8393x_get(s, width, 0);
> +            s->regs[SONIC_CTDA] = dp8393x_get(s, dp8393x_ttda(s),
> +                                              4 + 3 * s->regs[SONIC_TFC]);
>               if (s->regs[SONIC_CTDA] & SONIC_DESC_EOL) {
>                   /* EOL detected */
>                   break;
> @@ -762,7 +747,7 @@ static ssize_t dp8393x_receive(NetClientState *nc, const uint8_t * buf,
>       dp8393xState *s = qemu_get_nic_opaque(nc);
>       int packet_type;
>       uint32_t available, address;
> -    int width, rx_len, padded_len;
> +    int rx_len, padded_len;
>       uint32_t checksum;
>       int size;
>   
> @@ -775,10 +760,8 @@ static ssize_t dp8393x_receive(NetClientState *nc, const uint8_t * buf,
>   
>       rx_len = pkt_size + sizeof(checksum);
>       if (s->regs[SONIC_DCR] & SONIC_DCR_DW) {
> -        width = 2;
>           padded_len = ((rx_len - 1) | 3) + 1;
>       } else {
> -        width = 1;
>           padded_len = ((rx_len - 1) | 1) + 1;
>       }
>   
> @@ -799,11 +782,7 @@ static ssize_t dp8393x_receive(NetClientState *nc, const uint8_t * buf,
>       /* Check for EOL */
>       if (s->regs[SONIC_LLFA] & SONIC_DESC_EOL) {
>           /* Are we still in resource exhaustion? */
> -        size = sizeof(uint16_t) * 1 * width;
> -        address = dp8393x_crda(s) + sizeof(uint16_t) * 5 * width;
> -        address_space_read(&s->as, address, MEMTXATTRS_UNSPECIFIED,
> -                           s->data, size);
> -        s->regs[SONIC_LLFA] = dp8393x_get(s, width, 0);
> +        s->regs[SONIC_LLFA] = dp8393x_get(s, dp8393x_crda(s), 5);
>           if (s->regs[SONIC_LLFA] & SONIC_DESC_EOL) {
>               /* Still EOL ; stop reception */
>               return -1;
> @@ -811,11 +790,7 @@ static ssize_t dp8393x_receive(NetClientState *nc, const uint8_t * buf,
>           /* Link has been updated by host */
>   
>           /* Clear in_use */
> -        size = sizeof(uint16_t) * width;
> -        address = dp8393x_crda(s) + sizeof(uint16_t) * 6 * width;
> -        dp8393x_put(s, width, 0, 0);
> -        address_space_write(&s->as, address, MEMTXATTRS_UNSPECIFIED,
> -                            (uint8_t *)s->data, size);
> +        dp8393x_put(s, dp8393x_crda(s), 6, 0x0000);
>   
>           /* Move to next descriptor */
>           s->regs[SONIC_CRDA] = s->regs[SONIC_LLFA];
> @@ -869,32 +844,20 @@ static ssize_t dp8393x_receive(NetClientState *nc, const uint8_t * buf,
>   
>       /* Write status to memory */
>       trace_dp8393x_receive_write_status(dp8393x_crda(s));
> -    dp8393x_put(s, width, 0, s->regs[SONIC_RCR]); /* status */
> -    dp8393x_put(s, width, 1, rx_len); /* byte count */
> -    dp8393x_put(s, width, 2, s->regs[SONIC_TRBA0]); /* pkt_ptr0 */
> -    dp8393x_put(s, width, 3, s->regs[SONIC_TRBA1]); /* pkt_ptr1 */
> -    dp8393x_put(s, width, 4, s->regs[SONIC_RSC]); /* seq_no */
> -    size = sizeof(uint16_t) * 5 * width;
> -    address_space_write(&s->as, dp8393x_crda(s),
> -                        MEMTXATTRS_UNSPECIFIED,
> -                        s->data, size);
> +    dp8393x_put(s, dp8393x_crda(s), 0, s->regs[SONIC_RCR]); /* status */
> +    dp8393x_put(s, dp8393x_crda(s), 1, rx_len); /* byte count */
> +    dp8393x_put(s, dp8393x_crda(s), 2, s->regs[SONIC_TRBA0]); /* pkt_ptr0 */
> +    dp8393x_put(s, dp8393x_crda(s), 3, s->regs[SONIC_TRBA1]); /* pkt_ptr1 */
> +    dp8393x_put(s, dp8393x_crda(s), 4, s->regs[SONIC_RSC]); /* seq_no */
>   
>       /* Check link field */
> -    size = sizeof(uint16_t) * width;
> -    address_space_read(&s->as,
> -                       dp8393x_crda(s) + sizeof(uint16_t) * 5 * width,
> -                       MEMTXATTRS_UNSPECIFIED, s->data, size);
> -    s->regs[SONIC_LLFA] = dp8393x_get(s, width, 0);
> +    s->regs[SONIC_LLFA] = dp8393x_get(s, dp8393x_crda(s), 5);
>       if (s->regs[SONIC_LLFA] & SONIC_DESC_EOL) {
>           /* EOL detected */
>           s->regs[SONIC_ISR] |= SONIC_ISR_RDE;
>       } else {
>           /* Clear in_use */
> -        size = sizeof(uint16_t) * width;
> -        address = dp8393x_crda(s) + sizeof(uint16_t) * 6 * width;
> -        dp8393x_put(s, width, 0, 0);
> -        address_space_write(&s->as, address, MEMTXATTRS_UNSPECIFIED,
> -                            s->data, size);
> +        dp8393x_put(s, dp8393x_crda(s), 6, 0x0000);
>   
>           /* Move to next descriptor */
>           s->regs[SONIC_CRDA] = s->regs[SONIC_LLFA];

This seems like a nice tidy-up. I'll need a bit of time to give some more R-b and T-b 
tags since MacOS is running on a very diverged branch, so I'll need to pick through 
and update the changes to run across all my test images accordingly.

With this patch is it now possible to remove s->data completely?


ATB,

Mark.