1 From 58078a30038b578c26c532545448fe3746648390 Mon Sep 17 00:00:00 2001
2 From: Hauke Mehrtens <hauke@hauke-m.de>
3 Date: Thu, 29 Dec 2016 21:02:57 +0100
4 Subject: [PATCH] MIPS: lantiq: lock DMA register accesses for SMP
6 The DMA controller channel and port configuration is changed by
7 selecting the port or channel in one register and then update the
8 configuration in other registers. This has to be done in an atomic
9 operation. Previously only the local interrupts were deactivated which
10 works for single CPU systems. If the system supports SMP a better
11 locking is needed, use spinlocks instead.
12 On more recent SoCs (at least xrx200 and later) there are two memory
13 regions to change the configuration, there we could use one area for
14 each CPU and do not have to synchronize between the CPUs and more.
16 Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
18 arch/mips/lantiq/xway/dma.c | 38 ++++++++++++++++++++------------------
19 1 file changed, 20 insertions(+), 18 deletions(-)
21 --- a/arch/mips/lantiq/xway/dma.c
22 +++ b/arch/mips/lantiq/xway/dma.c
25 #include <linux/dma-mapping.h>
26 #include <linux/module.h>
27 +#include <linux/spinlock.h>
28 #include <linux/clk.h>
29 #include <linux/err.h>
32 ltq_dma_membase + (z))
34 static void __iomem *ltq_dma_membase;
35 +static DEFINE_SPINLOCK(ltq_dma_lock);
38 ltq_dma_enable_irq(struct ltq_dma_channel *ch)
42 - local_irq_save(flags);
43 + spin_lock_irqsave(<q_dma_lock, flags);
44 ltq_dma_w32(ch->nr, LTQ_DMA_CS);
45 ltq_dma_w32_mask(0, 1 << ch->nr, LTQ_DMA_IRNEN);
46 - local_irq_restore(flags);
47 + spin_unlock_irqrestore(<q_dma_lock, flags);
49 EXPORT_SYMBOL_GPL(ltq_dma_enable_irq);
51 @@ -77,10 +79,10 @@ ltq_dma_disable_irq(struct ltq_dma_chann
55 - local_irq_save(flags);
56 + spin_lock_irqsave(<q_dma_lock, flags);
57 ltq_dma_w32(ch->nr, LTQ_DMA_CS);
58 ltq_dma_w32_mask(1 << ch->nr, 0, LTQ_DMA_IRNEN);
59 - local_irq_restore(flags);
60 + spin_unlock_irqrestore(<q_dma_lock, flags);
62 EXPORT_SYMBOL_GPL(ltq_dma_disable_irq);
64 @@ -89,10 +91,10 @@ ltq_dma_ack_irq(struct ltq_dma_channel *
68 - local_irq_save(flags);
69 + spin_lock_irqsave(<q_dma_lock, flags);
70 ltq_dma_w32(ch->nr, LTQ_DMA_CS);
71 ltq_dma_w32(DMA_IRQ_ACK, LTQ_DMA_CIS);
72 - local_irq_restore(flags);
73 + spin_unlock_irqrestore(<q_dma_lock, flags);
75 EXPORT_SYMBOL_GPL(ltq_dma_ack_irq);
77 @@ -101,11 +103,11 @@ ltq_dma_open(struct ltq_dma_channel *ch)
81 - local_irq_save(flag);
82 + spin_lock_irqsave(<q_dma_lock, flag);
83 ltq_dma_w32(ch->nr, LTQ_DMA_CS);
84 ltq_dma_w32_mask(0, DMA_CHAN_ON, LTQ_DMA_CCTRL);
85 - ltq_dma_enable_irq(ch);
86 - local_irq_restore(flag);
87 + ltq_dma_w32_mask(0, 1 << ch->nr, LTQ_DMA_IRNEN);
88 + spin_unlock_irqrestore(<q_dma_lock, flag);
90 EXPORT_SYMBOL_GPL(ltq_dma_open);
92 @@ -114,11 +116,11 @@ ltq_dma_close(struct ltq_dma_channel *ch
96 - local_irq_save(flag);
97 + spin_lock_irqsave(<q_dma_lock, flag);
98 ltq_dma_w32(ch->nr, LTQ_DMA_CS);
99 ltq_dma_w32_mask(DMA_CHAN_ON, 0, LTQ_DMA_CCTRL);
100 - ltq_dma_disable_irq(ch);
101 - local_irq_restore(flag);
102 + ltq_dma_w32_mask(1 << ch->nr, 0, LTQ_DMA_IRNEN);
103 + spin_unlock_irqrestore(<q_dma_lock, flag);
105 EXPORT_SYMBOL_GPL(ltq_dma_close);
107 @@ -133,7 +135,7 @@ ltq_dma_alloc(struct ltq_dma_channel *ch
108 &ch->phys, GFP_ATOMIC);
109 memset(ch->desc_base, 0, LTQ_DESC_NUM * LTQ_DESC_SIZE);
111 - local_irq_save(flags);
112 + spin_lock_irqsave(<q_dma_lock, flags);
113 ltq_dma_w32(ch->nr, LTQ_DMA_CS);
114 ltq_dma_w32(ch->phys, LTQ_DMA_CDBA);
115 ltq_dma_w32(LTQ_DESC_NUM, LTQ_DMA_CDLEN);
116 @@ -142,7 +144,7 @@ ltq_dma_alloc(struct ltq_dma_channel *ch
117 ltq_dma_w32_mask(0, DMA_CHAN_RST, LTQ_DMA_CCTRL);
118 while (ltq_dma_r32(LTQ_DMA_CCTRL) & DMA_CHAN_RST)
120 - local_irq_restore(flags);
121 + spin_unlock_irqrestore(<q_dma_lock, flags);
125 @@ -152,11 +154,11 @@ ltq_dma_alloc_tx(struct ltq_dma_channel
129 - local_irq_save(flags);
130 + spin_lock_irqsave(<q_dma_lock, flags);
131 ltq_dma_w32(DMA_DESCPT, LTQ_DMA_CIE);
132 ltq_dma_w32_mask(0, 1 << ch->nr, LTQ_DMA_IRNEN);
133 ltq_dma_w32(DMA_WEIGHT | DMA_TX, LTQ_DMA_CCTRL);
134 - local_irq_restore(flags);
135 + spin_unlock_irqrestore(<q_dma_lock, flags);
137 EXPORT_SYMBOL_GPL(ltq_dma_alloc_tx);
139 @@ -167,11 +169,11 @@ ltq_dma_alloc_rx(struct ltq_dma_channel
143 - local_irq_save(flags);
144 + spin_lock_irqsave(<q_dma_lock, flags);
145 ltq_dma_w32(DMA_DESCPT, LTQ_DMA_CIE);
146 ltq_dma_w32_mask(0, 1 << ch->nr, LTQ_DMA_IRNEN);
147 ltq_dma_w32(DMA_WEIGHT, LTQ_DMA_CCTRL);
148 - local_irq_restore(flags);
149 + spin_unlock_irqrestore(<q_dma_lock, flags);
151 EXPORT_SYMBOL_GPL(ltq_dma_alloc_rx);