cxgb4: Replaced the backdoor mechanism to access the HW memory with PCIe Window method

Rip out a bunch of redundant PCI-E Memory Window Read/Write routines,
collapse the more general purpose routines into a single routine
thereby eliminating the need for a large stack frame (and extra data
copying) in the outer routine, change everything to use the improved
routine t4_memory_rw.

Based on origninal work by Casey Leedom <leedom@chelsio.com> and
Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Casey Leedom <leedom@chelsio.com>
Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/chelsio/cxgb4/cxgb4.h

@@ -654,6 +654,7 @@ struct adapter {
 	struct dentry *debugfs_root;
 
 	spinlock_t stats_lock;
+	spinlock_t win0_lock ____cacheline_aligned_in_smp;
 };
 
 /* Defined bit width of user definable filter tuples
@@ -960,8 +961,17 @@ int t4_wait_dev_ready(struct adapter *adap);
 int t4_link_start(struct adapter *adap, unsigned int mbox, unsigned int port,
 		  struct link_config *lc);
 int t4_restart_aneg(struct adapter *adap, unsigned int mbox, unsigned int port);
-int t4_memory_write(struct adapter *adap, int mtype, u32 addr, u32 len,
-		    __be32 *buf);
+
+#define T4_MEMORY_WRITE	0
+#define T4_MEMORY_READ	1
+int t4_memory_rw(struct adapter *adap, int win, int mtype, u32 addr, u32 len,
+		 __be32 *buf, int dir);
+static inline int t4_memory_write(struct adapter *adap, int mtype, u32 addr,
+				  u32 len, __be32 *buf)
+{
+	return t4_memory_rw(adap, 0, mtype, addr, len, buf, 0);
+}
+
 int t4_seeprom_wp(struct adapter *adapter, bool enable);
 int get_vpd_params(struct adapter *adapter, struct vpd_params *p);
 int t4_load_fw(struct adapter *adapter, const u8 *fw_data, unsigned int size);
@@ -1059,7 +1069,6 @@ int t4_ofld_eq_free(struct adapter *adap, unsigned int mbox, unsigned int pf,
 int t4_handle_fw_rpl(struct adapter *adap, const __be64 *rpl);
 void t4_db_full(struct adapter *adapter);
 void t4_db_dropped(struct adapter *adapter);
-int t4_mem_win_read_len(struct adapter *adap, u32 addr, __be32 *data, int len);
 int t4_fwaddrspace_write(struct adapter *adap, unsigned int mbox,
 			 u32 addr, u32 val);
 void t4_sge_decode_idma_state(struct adapter *adapter, int state);

drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c

@@ -3066,6 +3066,8 @@ static ssize_t mem_read(struct file *file, char __user *buf, size_t count,
 	loff_t avail = file_inode(file)->i_size;
 	unsigned int mem = (uintptr_t)file->private_data & 3;
 	struct adapter *adap = file->private_data - mem;
+	__be32 *data;
+	int ret;
 
 	if (pos < 0)
 		return -EINVAL;
@@ -3074,29 +3076,24 @@ static ssize_t mem_read(struct file *file, char __user *buf, size_t count,
 	if (count > avail - pos)
 		count = avail - pos;
 
-	while (count) {
-		size_t len;
-		int ret, ofst;
-		__be32 data[16];
+	data = t4_alloc_mem(count);
+	if (!data)
+		return -ENOMEM;
 
-		if ((mem == MEM_MC) || (mem == MEM_MC1))
-			ret = t4_mc_read(adap, mem % MEM_MC, pos, data, NULL);
-		else
-			ret = t4_edc_read(adap, mem, pos, data, NULL);
-		if (ret)
+	spin_lock(&adap->win0_lock);
+	ret = t4_memory_rw(adap, 0, mem, pos, count, data, T4_MEMORY_READ);
+	spin_unlock(&adap->win0_lock);
+	if (ret) {
+		t4_free_mem(data);
 		return ret;
+	}
+	ret = copy_to_user(buf, data, count);
 
-		ofst = pos % sizeof(data);
-		len = min(count, sizeof(data) - ofst);
-		if (copy_to_user(buf, (u8 *)data + ofst, len))
+	t4_free_mem(data);
+	if (ret)
 		return -EFAULT;
 
-		buf += len;
-		pos += len;
-		count -= len;
-	}
-	count = pos - *ppos;
-	*ppos = pos;
+	*ppos = pos + count;
 	return count;
 }
 
@@ -3757,7 +3754,11 @@ static int read_eq_indices(struct adapter *adap, u16 qid, u16 *pidx, u16 *cidx)
 	__be64 indices;
 	int ret;
 
-	ret = t4_mem_win_read_len(adap, addr, (__be32 *)&indices, 8);
+	spin_lock(&adap->win0_lock);
+	ret = t4_memory_rw(adap, 0, MEM_EDC0, addr,
+			   sizeof(indices), (__be32 *)&indices,
+			   T4_MEMORY_READ);
+	spin_unlock(&adap->win0_lock);
 	if (!ret) {
 		*cidx = (be64_to_cpu(indices) >> 25) & 0xffff;
 		*pidx = (be64_to_cpu(indices) >> 9) & 0xffff;
@@ -5076,7 +5077,7 @@ static int adap_init0_config(struct adapter *adapter, int reset)
 					      adapter->fn, 0, 1, params, val);
 			if (ret == 0) {
 				/*
-				 * For t4_memory_write() below addresses and
+				 * For t4_memory_rw() below addresses and
 				 * sizes have to be in terms of multiples of 4
 				 * bytes.  So, if the Configuration File isn't
 				 * a multiple of 4 bytes in length we'll have
@@ -5092,8 +5093,9 @@ static int adap_init0_config(struct adapter *adapter, int reset)
 				mtype = FW_PARAMS_PARAM_Y_GET(val[0]);
 				maddr = FW_PARAMS_PARAM_Z_GET(val[0]) << 16;
 
-				ret = t4_memory_write(adapter, mtype, maddr,
-						      size, data);
+				spin_lock(&adapter->win0_lock);
+				ret = t4_memory_rw(adapter, 0, mtype, maddr,
+						   size, data, T4_MEMORY_WRITE);
 				if (ret == 0 && resid != 0) {
 					union {
 						__be32 word;
@@ -5104,10 +5106,12 @@ static int adap_init0_config(struct adapter *adapter, int reset)
 					last.word = data[size >> 2];
 					for (i = resid; i < 4; i++)
 						last.buf[i] = 0;
-					ret = t4_memory_write(adapter, mtype,
+					ret = t4_memory_rw(adapter, 0, mtype,
 							   maddr + size,
-							      4, &last.word);
+							   4, &last.word,
+							   T4_MEMORY_WRITE);
 				}
+				spin_unlock(&adapter->win0_lock);
 			}
 		}
 

drivers/net/ethernet/chelsio/cxgb4/t4_hw.c

@@ -413,78 +413,41 @@ int t4_edc_read(struct adapter *adap, int idx, u32 addr, __be32 *data, u64 *ecc)
 	return 0;
 }
 
-/*
- *	t4_mem_win_rw - read/write memory through PCIE memory window
- *	@adap: the adapter
- *	@addr: address of first byte requested
- *	@data: MEMWIN0_APERTURE bytes of data containing the requested address
- *	@dir: direction of transfer 1 => read, 0 => write
- *
- *	Read/write MEMWIN0_APERTURE bytes of data from MC starting at a
- *	MEMWIN0_APERTURE-byte-aligned address that covers the requested
- *	address @addr.
- */
-static int t4_mem_win_rw(struct adapter *adap, u32 addr, __be32 *data, int dir)
-{
-	int i;
-	u32 win_pf = is_t4(adap->params.chip) ? 0 : V_PFNUM(adap->fn);
-
-	/*
-	 * Setup offset into PCIE memory window.  Address must be a
-	 * MEMWIN0_APERTURE-byte-aligned address.  (Read back MA register to
-	 * ensure that changes propagate before we attempt to use the new
-	 * values.)
-	 */
-	t4_write_reg(adap, PCIE_MEM_ACCESS_OFFSET,
-		     (addr & ~(MEMWIN0_APERTURE - 1)) | win_pf);
-	t4_read_reg(adap, PCIE_MEM_ACCESS_OFFSET);
-
-	/* Collecting data 4 bytes at a time upto MEMWIN0_APERTURE */
-	for (i = 0; i < MEMWIN0_APERTURE; i = i+0x4) {
-		if (dir)
-			*data++ = (__force __be32) t4_read_reg(adap,
-							(MEMWIN0_BASE + i));
-		else
-			t4_write_reg(adap, (MEMWIN0_BASE + i),
-				     (__force u32) *data++);
-	}
-
-	return 0;
-}
-
 /**
  *	t4_memory_rw - read/write EDC 0, EDC 1 or MC via PCIE memory window
  *	@adap: the adapter
+ *	@win: PCI-E Memory Window to use
  *	@mtype: memory type: MEM_EDC0, MEM_EDC1 or MEM_MC
  *	@addr: address within indicated memory type
  *	@len: amount of memory to transfer
  *	@buf: host memory buffer
- *	@dir: direction of transfer 1 => read, 0 => write
+ *	@dir: direction of transfer T4_MEMORY_READ (1) or T4_MEMORY_WRITE (0)
  *
  *	Reads/writes an [almost] arbitrary memory region in the firmware: the
- *	firmware memory address, length and host buffer must be aligned on
- *	32-bit boudaries.  The memory is transferred as a raw byte sequence
- *	from/to the firmware's memory.  If this memory contains data
- *	structures which contain multi-byte integers, it's the callers
- *	responsibility to perform appropriate byte order conversions.
+ *	firmware memory address and host buffer must be aligned on 32-bit
+ *	boudaries; the length may be arbitrary.  The memory is transferred as
+ *	a raw byte sequence from/to the firmware's memory.  If this memory
+ *	contains data structures which contain multi-byte integers, it's the
+ *	caller's responsibility to perform appropriate byte order conversions.
  */
-static int t4_memory_rw(struct adapter *adap, int mtype, u32 addr, u32 len,
-			__be32 *buf, int dir)
+int t4_memory_rw(struct adapter *adap, int win, int mtype, u32 addr,
+		 u32 len, __be32 *buf, int dir)
 {
-	u32 pos, start, end, offset, memoffset;
-	u32 edc_size, mc_size;
-	int ret = 0;
-	__be32 *data;
+	u32 pos, offset, resid, memoffset;
+	u32 edc_size, mc_size, win_pf, mem_reg, mem_aperture, mem_base;
 
-	/*
-	 * Argument sanity checks ...
+	/* Argument sanity checks ...
 	 */
-	if ((addr & 0x3) || (len & 0x3))
+	if (addr & 0x3)
 		return -EINVAL;
 
-	data = vmalloc(MEMWIN0_APERTURE);
-	if (!data)
-		return -ENOMEM;
+	/* It's convenient to be able to handle lengths which aren't a
+	 * multiple of 32-bits because we often end up transferring files to
+	 * the firmware.  So we'll handle that by normalizing the length here
+	 * and then handling any residual transfer at the end.
+	 */
+	resid = len & 0x3;
+	len -= resid;
 
 	/* Offset into the region of memory which is being accessed
 	 * MEM_EDC0 = 0
@@ -505,66 +468,98 @@ static int t4_memory_rw(struct adapter *adap, int mtype, u32 addr, u32 len,
 	/* Determine the PCIE_MEM_ACCESS_OFFSET */
 	addr = addr + memoffset;
 
-	/*
-	 * The underlaying EDC/MC read routines read MEMWIN0_APERTURE bytes
-	 * at a time so we need to round down the start and round up the end.
-	 * We'll start copying out of the first line at (addr - start) a word
-	 * at a time.
-	 */
-	start = addr & ~(MEMWIN0_APERTURE-1);
-	end = (addr + len + MEMWIN0_APERTURE-1) & ~(MEMWIN0_APERTURE-1);
-	offset = (addr - start)/sizeof(__be32);
-
-	for (pos = start; pos < end; pos += MEMWIN0_APERTURE, offset = 0) {
+	/* Each PCI-E Memory Window is programmed with a window size -- or
+	 * "aperture" -- which controls the granularity of its mapping onto
+	 * adapter memory.  We need to grab that aperture in order to know
+	 * how to use the specified window.  The window is also programmed
+	 * with the base address of the Memory Window in BAR0's address
+	 * space.  For T4 this is an absolute PCI-E Bus Address.  For T5
+	 * the address is relative to BAR0.
+	 */
+	mem_reg = t4_read_reg(adap,
+			      PCIE_MEM_ACCESS_REG(PCIE_MEM_ACCESS_BASE_WIN,
+						  win));
+	mem_aperture = 1 << (GET_WINDOW(mem_reg) + 10);
+	mem_base = GET_PCIEOFST(mem_reg) << 10;
+	if (is_t4(adap->params.chip))
+		mem_base -= adap->t4_bar0;
+	win_pf = is_t4(adap->params.chip) ? 0 : V_PFNUM(adap->fn);
 
-		/*
-		 * If we're writing, copy the data from the caller's memory
-		 * buffer
-		 */
-		if (!dir) {
-			/*
-			 * If we're doing a partial write, then we need to do
-			 * a read-modify-write ...
+	/* Calculate our initial PCI-E Memory Window Position and Offset into
+	 * that Window.
 	 */
-			if (offset || len < MEMWIN0_APERTURE) {
-				ret = t4_mem_win_rw(adap, pos, data, 1);
-				if (ret)
-					break;
-			}
-			while (offset < (MEMWIN0_APERTURE/sizeof(__be32)) &&
-			       len > 0) {
-				data[offset++] = *buf++;
-				len -= sizeof(__be32);
-			}
-		}
+	pos = addr & ~(mem_aperture-1);
+	offset = addr - pos;
 
-		/*
-		 * Transfer a block of memory and bail if there's an error.
+	/* Set up initial PCI-E Memory Window to cover the start of our
+	 * transfer.  (Read it back to ensure that changes propagate before we
+	 * attempt to use the new value.)
 	 */
-		ret = t4_mem_win_rw(adap, pos, data, dir);
-		if (ret)
-			break;
+	t4_write_reg(adap,
+		     PCIE_MEM_ACCESS_REG(PCIE_MEM_ACCESS_OFFSET, win),
+		     pos | win_pf);
+	t4_read_reg(adap,
+		    PCIE_MEM_ACCESS_REG(PCIE_MEM_ACCESS_OFFSET, win));
 
-		/*
-		 * If we're reading, copy the data into the caller's memory
-		 * buffer.
+	/* Transfer data to/from the adapter as long as there's an integral
+	 * number of 32-bit transfers to complete.
 	 */
-		if (dir)
-			while (offset < (MEMWIN0_APERTURE/sizeof(__be32)) &&
-			       len > 0) {
-				*buf++ = data[offset++];
+	while (len > 0) {
+		if (dir == T4_MEMORY_READ)
+			*buf++ = (__force __be32) t4_read_reg(adap,
+							mem_base + offset);
+		else
+			t4_write_reg(adap, mem_base + offset,
+				     (__force u32) *buf++);
+		offset += sizeof(__be32);
 		len -= sizeof(__be32);
+
+		/* If we've reached the end of our current window aperture,
+		 * move the PCI-E Memory Window on to the next.  Note that
+		 * doing this here after "len" may be 0 allows us to set up
+		 * the PCI-E Memory Window for a possible final residual
+		 * transfer below ...
+		 */
+		if (offset == mem_aperture) {
+			pos += mem_aperture;
+			offset = 0;
+			t4_write_reg(adap,
+				     PCIE_MEM_ACCESS_REG(PCIE_MEM_ACCESS_OFFSET,
+							 win), pos | win_pf);
+			t4_read_reg(adap,
+				    PCIE_MEM_ACCESS_REG(PCIE_MEM_ACCESS_OFFSET,
+							win));
+		}
+	}
+
+	/* If the original transfer had a length which wasn't a multiple of
+	 * 32-bits, now's where we need to finish off the transfer of the
+	 * residual amount.  The PCI-E Memory Window has already been moved
+	 * above (if necessary) to cover this final transfer.
+	 */
+	if (resid) {
+		union {
+			__be32 word;
+			char byte[4];
+		} last;
+		unsigned char *bp;
+		int i;
+
+		if (dir == T4_MEMORY_WRITE) {
+			last.word = (__force __be32) t4_read_reg(adap,
+							mem_base + offset);
+			for (bp = (unsigned char *)buf, i = resid; i < 4; i++)
+				bp[i] = last.byte[i];
+		} else {
+			last.word = *buf;
+			for (i = resid; i < 4; i++)
+				last.byte[i] = 0;
+			t4_write_reg(adap, mem_base + offset,
+				     (__force u32) last.word);
 		}
 	}
 
-	vfree(data);
-	return ret;
-}
-
-int t4_memory_write(struct adapter *adap, int mtype, u32 addr, u32 len,
-		    __be32 *buf)
-{
-	return t4_memory_rw(adap, mtype, addr, len, buf, 0);
+	return 0;
 }
 
 #define EEPROM_STAT_ADDR   0x7bfc
@@ -2528,39 +2523,6 @@ int t4_fwaddrspace_write(struct adapter *adap, unsigned int mbox,
 	return t4_wr_mbox(adap, mbox, &c, sizeof(c), NULL);
 }
 
-/**
- *     t4_mem_win_read_len - read memory through PCIE memory window
- *     @adap: the adapter
- *     @addr: address of first byte requested aligned on 32b.
- *     @data: len bytes to hold the data read
- *     @len: amount of data to read from window.  Must be <=
- *            MEMWIN0_APERATURE after adjusting for 16B for T4 and
- *            128B for T5 alignment requirements of the the memory window.
- *
- *     Read len bytes of data from MC starting at @addr.
- */
-int t4_mem_win_read_len(struct adapter *adap, u32 addr, __be32 *data, int len)
-{
-	int i, off;
-	u32 win_pf = is_t4(adap->params.chip) ? 0 : V_PFNUM(adap->fn);
-
-	/* Align on a 2KB boundary.
-	 */
-	off = addr & MEMWIN0_APERTURE;
-	if ((addr & 3) || (len + off) > MEMWIN0_APERTURE)
-		return -EINVAL;
-
-	t4_write_reg(adap, PCIE_MEM_ACCESS_OFFSET,
-		     (addr & ~MEMWIN0_APERTURE) | win_pf);
-	t4_read_reg(adap, PCIE_MEM_ACCESS_OFFSET);
-
-	for (i = 0; i < len; i += 4)
-		*data++ = (__force __be32) t4_read_reg(adap,
-						(MEMWIN0_BASE + off + i));
-
-	return 0;
-}
-
 /**
  *	t4_mdio_rd - read a PHY register through MDIO
  *	@adap: the adapter

drivers/net/ethernet/chelsio/cxgb4/t4_regs.h

@@ -400,6 +400,7 @@
 #define  WINDOW_MASK     0x000000ffU
 #define  WINDOW_SHIFT    0
 #define  WINDOW(x)       ((x) << WINDOW_SHIFT)
+#define  GET_WINDOW(x)	 (((x) >> WINDOW_SHIFT) & WINDOW_MASK)
 #define PCIE_MEM_ACCESS_OFFSET 0x306c
 #define ENABLE	(1U << 30)
 #define FUNCTION(x) ((x) << 12)