[ARM] pxa/dma: add debugfs entries

Add some debug information for PXA DMA :
 - descriptors queued
 - channels state
 - global state

--
Since V1: reverted to old register access (no more dma_readl() or dma_writel()).
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>

arch/arm/plat-pxa/dma.c

@@ -17,22 +17,266 @@
 #include <linux/kernel.h>
 #include <linux/interrupt.h>
 #include <linux/errno.h>
+#include <linux/dma-mapping.h>
 
 #include <asm/system.h>
 #include <asm/irq.h>
+#include <asm/memory.h>
 #include <mach/hardware.h>
 #include <mach/dma.h>
 
+#define DMA_DEBUG_NAME		"pxa_dma"
+#define DMA_MAX_REQUESTERS	64
+
 struct dma_channel {
 	char *name;
 	pxa_dma_prio prio;
 	void (*irq_handler)(int, void *);
 	void *data;
+	spinlock_t lock;
 };
 
 static struct dma_channel *dma_channels;
 static int num_dma_channels;
 
+/*
+ * Debug fs
+ */
+#ifdef CONFIG_DEBUG_FS
+#include <linux/debugfs.h>
+#include <linux/uaccess.h>
+#include <linux/seq_file.h>
+
+static struct dentry *dbgfs_root, *dbgfs_state, **dbgfs_chan;
+
+static int dbg_show_requester_chan(struct seq_file *s, void *p)
+{
+	int pos = 0;
+	int chan = (int)s->private;
+	int i;
+	u32 drcmr;
+
+	pos += seq_printf(s, "DMA channel %d requesters list :\n", chan);
+	for (i = 0; i < DMA_MAX_REQUESTERS; i++) {
+		drcmr = DRCMR(i);
+		if ((drcmr & DRCMR_CHLNUM) == chan)
+			pos += seq_printf(s, "\tRequester %d (MAPVLD=%d)\n", i,
+					  !!(drcmr & DRCMR_MAPVLD));
+	}
+	return pos;
+}
+
+static inline int dbg_burst_from_dcmd(u32 dcmd)
+{
+	int burst = (dcmd >> 16) & 0x3;
+
+	return burst ? 4 << burst : 0;
+}
+
+static int is_phys_valid(unsigned long addr)
+{
+	return pfn_valid(__phys_to_pfn(addr));
+}
+
+#define DCSR_STR(flag) (dcsr & DCSR_##flag ? #flag" " : "")
+#define DCMD_STR(flag) (dcmd & DCMD_##flag ? #flag" " : "")
+
+static int dbg_show_descriptors(struct seq_file *s, void *p)
+{
+	int pos = 0;
+	int chan = (int)s->private;
+	int i, max_show = 20, burst, width;
+	u32 dcmd;
+	unsigned long phys_desc;
+	struct pxa_dma_desc *desc;
+	unsigned long flags;
+
+	spin_lock_irqsave(&dma_channels[chan].lock, flags);
+	phys_desc = DDADR(chan);
+
+	pos += seq_printf(s, "DMA channel %d descriptors :\n", chan);
+	pos += seq_printf(s, "[%03d] First descriptor unknown\n", 0);
+	for (i = 1; i < max_show && is_phys_valid(phys_desc); i++) {
+		desc = phys_to_virt(phys_desc);
+		dcmd = desc->dcmd;
+		burst = dbg_burst_from_dcmd(dcmd);
+		width = (1 << ((dcmd >> 14) & 0x3)) >> 1;
+
+		pos += seq_printf(s, "[%03d] Desc at %08lx(virt %p)\n",
+				  i, phys_desc, desc);
+		pos += seq_printf(s, "\tDDADR = %08x\n", desc->ddadr);
+		pos += seq_printf(s, "\tDSADR = %08x\n", desc->dsadr);
+		pos += seq_printf(s, "\tDTADR = %08x\n", desc->dtadr);
+		pos += seq_printf(s, "\tDCMD  = %08x (%s%s%s%s%s%s%sburst=%d"
+				  " width=%d len=%d)\n",
+				  dcmd,
+				  DCMD_STR(INCSRCADDR), DCMD_STR(INCTRGADDR),
+				  DCMD_STR(FLOWSRC), DCMD_STR(FLOWTRG),
+				  DCMD_STR(STARTIRQEN), DCMD_STR(ENDIRQEN),
+				  DCMD_STR(ENDIAN), burst, width,
+				  dcmd & DCMD_LENGTH);
+		phys_desc = desc->ddadr;
+	}
+	if (i == max_show)
+		pos += seq_printf(s, "[%03d] Desc at %08lx ... max display reached\n",
+				  i, phys_desc);
+	else
+		pos += seq_printf(s, "[%03d] Desc at %08lx is %s\n",
+				  i, phys_desc, phys_desc == DDADR_STOP ?
+				  "DDADR_STOP" : "invalid");
+
+	spin_unlock_irqrestore(&dma_channels[chan].lock, flags);
+	return pos;
+}
+
+static int dbg_show_chan_state(struct seq_file *s, void *p)
+{
+	int pos = 0;
+	int chan = (int)s->private;
+	u32 dcsr, dcmd;
+	int burst, width;
+	static char *str_prio[] = { "high", "normal", "low" };
+
+	dcsr = DCSR(chan);
+	dcmd = DCMD(chan);
+	burst = dbg_burst_from_dcmd(dcmd);
+	width = (1 << ((dcmd >> 14) & 0x3)) >> 1;
+
+	pos += seq_printf(s, "DMA channel %d\n", chan);
+	pos += seq_printf(s, "\tPriority : %s\n",
+			  str_prio[dma_channels[chan].prio]);
+	pos += seq_printf(s, "\tUnaligned transfer bit: %s\n",
+			  DALGN & (1 << chan) ? "yes" : "no");
+	pos += seq_printf(s, "\tDCSR  = %08x (%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s)\n",
+			  dcsr, DCSR_STR(RUN), DCSR_STR(NODESC),
+			  DCSR_STR(STOPIRQEN), DCSR_STR(EORIRQEN),
+			  DCSR_STR(EORJMPEN), DCSR_STR(EORSTOPEN),
+			  DCSR_STR(SETCMPST), DCSR_STR(CLRCMPST),
+			  DCSR_STR(CMPST), DCSR_STR(EORINTR), DCSR_STR(REQPEND),
+			  DCSR_STR(STOPSTATE), DCSR_STR(ENDINTR),
+			  DCSR_STR(STARTINTR), DCSR_STR(BUSERR));
+
+	pos += seq_printf(s, "\tDCMD  = %08x (%s%s%s%s%s%s%sburst=%d width=%d"
+			  " len=%d)\n",
+			  dcmd,
+			  DCMD_STR(INCSRCADDR), DCMD_STR(INCTRGADDR),
+			  DCMD_STR(FLOWSRC), DCMD_STR(FLOWTRG),
+			  DCMD_STR(STARTIRQEN), DCMD_STR(ENDIRQEN),
+			  DCMD_STR(ENDIAN), burst, width, dcmd & DCMD_LENGTH);
+	pos += seq_printf(s, "\tDSADR = %08x\n", DSADR(chan));
+	pos += seq_printf(s, "\tDTADR = %08x\n", DTADR(chan));
+	pos += seq_printf(s, "\tDDADR = %08x\n", DDADR(chan));
+	return pos;
+}
+
+static int dbg_show_state(struct seq_file *s, void *p)
+{
+	int pos = 0;
+
+	/* basic device status */
+	pos += seq_printf(s, "DMA engine status\n");
+	pos += seq_printf(s, "\tChannel number: %d\n", num_dma_channels);
+
+	return pos;
+}
+
+#define DBGFS_FUNC_DECL(name) \
+static int dbg_open_##name(struct inode *inode, struct file *file) \
+{ \
+	return single_open(file, dbg_show_##name, inode->i_private); \
+} \
+static const struct file_operations dbg_fops_##name = { \
+	.owner		= THIS_MODULE, \
+	.open		= dbg_open_##name, \
+	.llseek		= seq_lseek, \
+	.read		= seq_read, \
+	.release	= single_release, \
+}
+
+DBGFS_FUNC_DECL(state);
+DBGFS_FUNC_DECL(chan_state);
+DBGFS_FUNC_DECL(descriptors);
+DBGFS_FUNC_DECL(requester_chan);
+
+static struct dentry *pxa_dma_dbg_alloc_chan(int ch, struct dentry *chandir)
+{
+	char chan_name[11];
+	struct dentry *chan, *chan_state = NULL, *chan_descr = NULL;
+	struct dentry *chan_reqs = NULL;
+	void *dt;
+
+	scnprintf(chan_name, sizeof(chan_name), "%d", ch);
+	chan = debugfs_create_dir(chan_name, chandir);
+	dt = (void *)ch;
+
+	if (chan)
+		chan_state = debugfs_create_file("state", 0400, chan, dt,
+						 &dbg_fops_chan_state);
+	if (chan_state)
+		chan_descr = debugfs_create_file("descriptors", 0400, chan, dt,
+						 &dbg_fops_descriptors);
+	if (chan_descr)
+		chan_reqs = debugfs_create_file("requesters", 0400, chan, dt,
+						&dbg_fops_requester_chan);
+	if (!chan_reqs)
+		goto err_state;
+
+	return chan;
+
+err_state:
+	debugfs_remove_recursive(chan);
+	return NULL;
+}
+
+static void pxa_dma_init_debugfs(void)
+{
+	int i;
+	struct dentry *chandir;
+
+	dbgfs_root = debugfs_create_dir(DMA_DEBUG_NAME, NULL);
+	if (IS_ERR(dbgfs_root) || !dbgfs_root)
+		goto err_root;
+
+	dbgfs_state = debugfs_create_file("state", 0400, dbgfs_root, NULL,
+					  &dbg_fops_state);
+	if (!dbgfs_state)
+		goto err_state;
+
+	dbgfs_chan = kmalloc(sizeof(*dbgfs_state) * num_dma_channels,
+			     GFP_KERNEL);
+	if (!dbgfs_state)
+		goto err_alloc;
+
+	chandir = debugfs_create_dir("channels", dbgfs_root);
+	if (!chandir)
+		goto err_chandir;
+
+	for (i = 0; i < num_dma_channels; i++) {
+		dbgfs_chan[i] = pxa_dma_dbg_alloc_chan(i, chandir);
+		if (!dbgfs_chan[i])
+			goto err_chans;
+	}
+
+	return;
+err_chans:
+err_chandir:
+	kfree(dbgfs_chan);
+err_alloc:
+err_state:
+	debugfs_remove_recursive(dbgfs_root);
+err_root:
+	pr_err("pxa_dma: debugfs is not available\n");
+}
+
+static void __exit pxa_dma_cleanup_debugfs(void)
+{
+	debugfs_remove_recursive(dbgfs_root);
+}
+#else
+static inline void pxa_dma_init_debugfs(void) {}
+static inline void pxa_dma_cleanup_debugfs(void) {}
+#endif
+
 int pxa_request_dma (char *name, pxa_dma_prio prio,
 			void (*irq_handler)(int, void *),
 			void *data)
@@ -130,6 +374,7 @@ int __init pxa_init_dma(int irq, int num_ch)
 	for (i = 0; i < num_ch; i++) {
 		DCSR(i) = 0;
 		dma_channels[i].prio = min((i & 0xf) >> 2, DMA_PRIO_LOW);
+		spin_lock_init(&dma_channels[i].lock);
 	}
 
 	ret = request_irq(irq, dma_irq_handler, IRQF_DISABLED, "DMA", NULL);
@@ -138,7 +383,9 @@ int __init pxa_init_dma(int irq, int num_ch)
 		kfree(dma_channels);
 		return ret;
 	}
-
 	num_dma_channels = num_ch;
+
+	pxa_dma_init_debugfs();
+
 	return 0;
 }