On Fri, Feb 10, 2017 at 11:20 PM, Dan Williams <dan.j.williams@xxxxxxxxx> wrote: > On Fri, Feb 10, 2017 at 1:07 AM, Anup Patel <anup.patel@xxxxxxxxxxxx> wrote: >> The Broadcom stream buffer accelerator (SBA) provides offloading >> capabilities for RAID operations. This SBA offload engine is >> accessible via Broadcom SoC specific ring manager. >> >> This patch adds Broadcom SBA RAID driver which provides one >> DMA device with RAID capabilities using one or more Broadcom >> SoC specific ring manager channels. The SBA RAID driver in its >> current shape implements memcpy, xor, and pq operations. >> >> Signed-off-by: Anup Patel <anup.patel@xxxxxxxxxxxx> >> Reviewed-by: Ray Jui <ray.jui@xxxxxxxxxxxx> >> --- >> drivers/dma/Kconfig | 13 + >> drivers/dma/Makefile | 1 + >> drivers/dma/bcm-sba-raid.c | 1711 ++++++++++++++++++++++++++++++++++++++++++++ >> 3 files changed, 1725 insertions(+) >> create mode 100644 drivers/dma/bcm-sba-raid.c >> >> diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig >> index 263495d..bf8fb84 100644 >> --- a/drivers/dma/Kconfig >> +++ b/drivers/dma/Kconfig >> @@ -99,6 +99,19 @@ config AXI_DMAC >> controller is often used in Analog Device's reference designs for FPGA >> platforms. >> >> +config BCM_SBA_RAID >> + tristate "Broadcom SBA RAID engine support" >> + depends on (ARM64 && MAILBOX && RAID6_PQ) || COMPILE_TEST >> + select DMA_ENGINE >> + select DMA_ENGINE_RAID >> + select ASYNC_TX_ENABLE_CHANNEL_SWITCH > > ASYNC_TX_ENABLE_CHANNEL_SWITCH violates the DMA mapping API and > Russell has warned it's especially problematic on ARM [1]. If you > need channel switching for this offload engine to be useful then you > need to move DMA mapping and channel switching responsibilities to MD > itself. > > [1]: http://lists.infradead.org/pipermail/linux-arm-kernel/2011-January/036753.html Actually driver works fine with/without ASYNC_TX_ENABLE_CHANNEL_SWITCH enabled so I am fine with removing dependency on this config option. > > > [..] >> diff --git a/drivers/dma/bcm-sba-raid.c b/drivers/dma/bcm-sba-raid.c >> new file mode 100644 >> index 0000000..bab9918 >> --- /dev/null >> +++ b/drivers/dma/bcm-sba-raid.c >> @@ -0,0 +1,1711 @@ >> +/* >> + * Copyright (C) 2017 Broadcom >> + * >> + * This program is free software; you can redistribute it and/or modify >> + * it under the terms of the GNU General Public License version 2 as >> + * published by the Free Software Foundation. >> + */ >> + >> +/* >> + * Broadcom SBA RAID Driver >> + * >> + * The Broadcom stream buffer accelerator (SBA) provides offloading >> + * capabilities for RAID operations. The SBA offload engine is accessible >> + * via Broadcom SoC specific ring manager. Two or more offload engines >> + * can share same Broadcom SoC specific ring manager due to this Broadcom >> + * SoC specific ring manager driver is implemented as a mailbox controller >> + * driver and offload engine drivers are implemented as mallbox clients. >> + * >> + * Typically, Broadcom SoC specific ring manager will implement larger >> + * number of hardware rings over one or more SBA hardware devices. By >> + * design, the internal buffer size of SBA hardware device is limited >> + * but all offload operations supported by SBA can be broken down into >> + * multiple small size requests and executed parallely on multiple SBA >> + * hardware devices for achieving high through-put. >> + * >> + * The Broadcom SBA RAID driver does not require any register programming >> + * except submitting request to SBA hardware device via mailbox channels. >> + * This driver implements a DMA device with one DMA channel using a set >> + * of mailbox channels provided by Broadcom SoC specific ring manager >> + * driver. To exploit parallelism (as described above), all DMA request >> + * coming to SBA RAID DMA channel are broken down to smaller requests >> + * and submitted to multiple mailbox channels in round-robin fashion. >> + * For having more SBA DMA channels, we can create more SBA device nodes >> + * in Broadcom SoC specific DTS based on number of hardware rings supported >> + * by Broadcom SoC ring manager. >> + */ >> + >> +#include <linux/bitops.h> >> +#include <linux/dma-mapping.h> >> +#include <linux/dmaengine.h> >> +#include <linux/list.h> >> +#include <linux/mailbox_client.h> >> +#include <linux/mailbox/brcm-message.h> >> +#include <linux/module.h> >> +#include <linux/of_device.h> >> +#include <linux/slab.h> >> +#include <linux/raid/pq.h> >> + >> +#include "dmaengine.h" >> + >> +/* SBA command helper macros */ >> +#define SBA_DEC(_d, _s, _m) (((_d) >> (_s)) & (_m)) >> +#define SBA_ENC(_d, _v, _s, _m) \ >> + do { \ >> + (_d) &= ~((u64)(_m) << (_s)); \ >> + (_d) |= (((u64)(_v) & (_m)) << (_s)); \ >> + } while (0) > > Reusing a macro argument multiple times is problematic, consider > SBA_ENC(..., arg++, ...), and hiding assignments in a macro make this > hard to read. The compiler should inline it properly if you just make > this a function that returns a value. You could also mark it __pure. OK, I will make SBA_ENC as "static inline __pure" function. > > [..] >> + >> +static struct sba_request *sba_alloc_request(struct sba_device *sba) >> +{ >> + unsigned long flags; >> + struct sba_request *req = NULL; >> + >> + spin_lock_irqsave(&sba->reqs_lock, flags); >> + >> + if (!list_empty(&sba->reqs_free_list)) { >> + req = list_first_entry(&sba->reqs_free_list, >> + struct sba_request, >> + node); > > You could use list_first_entry_or_null() here. OK, will use this. > > [..] >> + >> +/* Note: Must be called with sba->reqs_lock held */ >> +static void _sba_pending_request(struct sba_device *sba, >> + struct sba_request *req) >> +{ > > You can validate the locking assumptions here with > lockdep_assert_head(sba->reqs_lock). OK, will try this. > > [..] >> + >> +static void sba_cleanup_nonpending_requests(struct sba_device *sba) >> +{ >> + unsigned long flags; >> + struct sba_request *req, *req1; >> + >> + spin_lock_irqsave(&sba->reqs_lock, flags); >> + >> + /* Freeup all alloced request */ >> + list_for_each_entry_safe(req, req1, &sba->reqs_alloc_list, node) { >> + _sba_free_request(sba, req); >> + } >> + >> + /* Freeup all received request */ >> + list_for_each_entry_safe(req, req1, &sba->reqs_received_list, node) { >> + _sba_free_request(sba, req); >> + } >> + >> + /* Freeup all completed request */ >> + list_for_each_entry_safe(req, req1, &sba->reqs_completed_list, node) { >> + _sba_free_request(sba, req); >> + } >> + >> + /* Set all active requests as aborted */ >> + list_for_each_entry_safe(req, req1, &sba->reqs_active_list, node) { >> + _sba_abort_request(sba, req); >> + } > > In some parts of the driver you leave off unneeded braces like the for > loop in sba_prep_dma_pq(), and in some case you include them. I'd say > remove them if they're not necessary, but either way make it > consistent across the driver. I think I relied too much on checkpatch.pl to catch this kind of coding-style issues. I will fix this. Thanks for catching. > > [..] >> + >> +static struct dma_async_tx_descriptor * >> +sba_prep_dma_pq(struct dma_chan *dchan, dma_addr_t *dst, dma_addr_t *src, >> + u32 src_cnt, const u8 *scf, size_t len, unsigned long flags) >> +{ >> + u32 i, dst_q_index; >> + size_t req_len; >> + bool slow = false; >> + dma_addr_t off = 0; >> + dma_addr_t *dst_p = NULL, *dst_q = NULL; >> + struct sba_device *sba = to_sba_device(dchan); >> + struct sba_request *first = NULL, *req; >> + >> + /* Sanity checks */ >> + if (unlikely(src_cnt > sba->max_pq_srcs)) >> + return NULL; >> + for (i = 0; i < src_cnt; i++) >> + if (sba->max_pq_coefs <= raid6_gflog[scf[i]]) >> + slow = true; > > Thanks, yes, I do think this is cleaner here than in async_tx itself. > > [..] >> +static void sba_receive_message(struct mbox_client *cl, void *msg) >> +{ >> + unsigned long flags; >> + struct brcm_message *m = msg; >> + struct sba_request *req = m->ctx, *req1; >> + struct sba_device *sba = req->sba; >> + >> + /* Error count if message has error */ >> + if (m->error < 0) { >> + dev_err(sba->dev, "%s got message with error %d", >> + dma_chan_name(&sba->dma_chan), m->error); >> + } >> + >> + /* Mark request as received */ >> + sba_received_request(req); >> + >> + /* Wait for all chained requests to be completed */ >> + if (atomic_dec_return(&req->first->next_pending_count)) >> + goto done; >> + >> + /* Point to first request */ >> + req = req->first; >> + >> + /* Update request */ >> + if (req->state == SBA_REQUEST_STATE_RECEIVED) >> + sba_dma_tx_actions(req); >> + else >> + sba_free_chained_requests(req); >> + >> + spin_lock_irqsave(&sba->reqs_lock, flags); >> + >> + /* Re-check all completed request waiting for 'ack' */ >> + list_for_each_entry_safe(req, req1, &sba->reqs_completed_list, node) { >> + spin_unlock_irqrestore(&sba->reqs_lock, flags); >> + sba_dma_tx_actions(req); > > You've now required all callback paths to be hardirq safe whereas > previously the callbacks only assumed softirq exclusion. Have you run > this with CONFIG_PROVE_LOCKING enabled? We have run stress tests on driver with multiple threads trying to submit txn. I will certainly try CONFIG_PROVE_LOCKING to be double sure. Thanks, Anup
