On Fri, Feb 10, 2017 at 1:07 AM, Anup Patel <anup.pa...@broadcom.com> 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.pa...@broadcom.com> > Reviewed-by: Ray Jui <ray....@broadcom.com> > --- > 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 [..] > 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. [..] > + > +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. [..] > + > +/* 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). [..] > + > +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. [..] > + > +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?
