[patch 10/14] cio: provide helper functions for fcx enabled I/O

[Martin Schwidefsky]

From: Peter Oberparleiter <peter.oberparleiter@xxxxxxxxxx>

Provide functions which can be used to incrementally construct fcx
enabled I/O control blocks.

Signed-off-by: Peter Oberparleiter <peter.oberparleiter@xxxxxxxxxx>
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
---

 drivers/s390/cio/Makefile |    3 
 drivers/s390/cio/itcw.c   |  327 ++++++++++++++++++++++++++++++++++++++++++++++
 include/asm-s390/itcw.h   |   30 ++++
 3 files changed, 359 insertions(+), 1 deletion(-)

Index: quilt-2.6/drivers/s390/cio/itcw.c
===================================================================
--- /dev/null
+++ quilt-2.6/drivers/s390/cio/itcw.c
@@ -0,0 +1,327 @@
+/*
+ *  Functions for incremental construction of fcx enabled I/O control blocks.
+ *
+ *    Copyright IBM Corp. 2008
+ *    Author(s): Peter Oberparleiter <peter.oberparleiter@xxxxxxxxxx>
+ */
+
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <asm/fcx.h>
+#include <asm/itcw.h>
+
+/**
+ * struct itcw - incremental tcw helper data type
+ *
+ * This structure serves as a handle for the incremental construction of a
+ * tcw and associated tccb, tsb, data tidaw-list plus an optional interrogate
+ * tcw and associated data. The data structures are contained inside a single
+ * contiguous buffer provided by the user.
+ *
+ * The itcw construction functions take care of overall data integrity:
+ * - reset unused fields to zero
+ * - fill in required pointers
+ * - ensure required alignment for data structures
+ * - prevent data structures to cross 4k-byte boundary where required
+ * - calculate tccb-related length fields
+ * - optionally provide ready-made interrogate tcw and associated structures
+ *
+ * Restrictions apply to the itcws created with these construction functions:
+ * - tida only supported for data address, not for tccb
+ * - only contiguous tidaw-lists (no ttic)
+ * - total number of bytes required per itcw may not exceed 4k bytes
+ * - either read or write operation (may not work with r=0 and w=0)
+ *
+ * Example:
+ * struct itcw *itcw;
+ * void *buffer;
+ * size_t size;
+ *
+ * size = itcw_calc_size(1, 2, 0);
+ * buffer = kmalloc(size, GFP_DMA);
+ * if (!buffer)
+ *	return -ENOMEM;
+ * itcw = itcw_init(buffer, size, ITCW_OP_READ, 1, 2, 0);
+ * if (IS_ERR(itcw))
+ *	return PTR_ER(itcw);
+ * itcw_add_dcw(itcw, 0x2, 0, NULL, 0, 72);
+ * itcw_add_tidaw(itcw, 0, 0x30000, 20);
+ * itcw_add_tidaw(itcw, 0, 0x40000, 52);
+ * itcw_finalize(itcw);
+ *
+ */
+struct itcw {
+	struct tcw *tcw;
+	struct tcw *intrg_tcw;
+	int num_tidaws;
+	int max_tidaws;
+	int intrg_num_tidaws;
+	int intrg_max_tidaws;
+};
+
+/**
+ * itcw_get_tcw - return pointer to tcw associated with the itcw
+ * @itcw: address of the itcw
+ *
+ * Return pointer to the tcw associated with the itcw.
+ */
+struct tcw *itcw_get_tcw(struct itcw *itcw)
+{
+	return itcw->tcw;
+}
+EXPORT_SYMBOL(itcw_get_tcw);
+
+/**
+ * itcw_calc_size - return the size of an itcw with the given parameters
+ * @intrg: if non-zero, add an interrogate tcw
+ * @max_tidaws: maximum number of tidaws to be used for data addressing or zero
+ * if no tida is to be used.
+ * @intrg_max_tidaws: maximum number of tidaws to be used for data addressing
+ * by the interrogate tcw, if specified
+ *
+ * Calculate and return the number of bytes required to hold an itcw with the
+ * given parameters and assuming tccbs with maximum size.
+ *
+ * Note that the resulting size also contains bytes needed for alignment
+ * padding as well as padding to ensure that data structures don't cross a
+ * 4k-boundary where required.
+ */
+size_t itcw_calc_size(int intrg, int max_tidaws, int intrg_max_tidaws)
+{
+	size_t len;
+
+	/* Main data. */
+	len = sizeof(struct itcw);
+	len += /* TCW */ sizeof(struct tcw) + /* TCCB */ TCCB_MAX_SIZE +
+	       /* TSB */ sizeof(struct tsb) +
+	       /* TIDAL */ max_tidaws * sizeof(struct tidaw);
+	/* Interrogate data. */
+	if (intrg) {
+		len += /* TCW */ sizeof(struct tcw) + /* TCCB */ TCCB_MAX_SIZE +
+		       /* TSB */ sizeof(struct tsb) +
+		       /* TIDAL */ intrg_max_tidaws * sizeof(struct tidaw);
+	}
+	/* Maximum required alignment padding. */
+	len += /* Initial TCW */ 63 + /* Interrogate TCCB */ 7;
+	/* Maximum padding for structures that may not cross 4k boundary. */
+	if ((max_tidaws > 0) || (intrg_max_tidaws > 0))
+		len += max(max_tidaws, intrg_max_tidaws) *
+		       sizeof(struct tidaw) - 1;
+	return len;
+}
+EXPORT_SYMBOL(itcw_calc_size);
+
+#define CROSS4K(x, l)	(((x) & ~4095) != ((x + l) & ~4095))
+
+static inline void *fit_chunk(addr_t *start, addr_t end, size_t len,
+			      int align, int check_4k)
+{
+	addr_t addr;
+
+	addr = ALIGN(*start, align);
+	if (check_4k && CROSS4K(addr, len)) {
+		addr = ALIGN(addr, 4096);
+		addr = ALIGN(addr, align);
+	}
+	if (addr + len > end)
+		return ERR_PTR(-ENOSPC);
+	*start = addr + len;
+	return (void *) addr;
+}
+
+/**
+ * itcw_init - initialize incremental tcw data structure
+ * @buffer: address of buffer to use for data structures
+ * @size: number of bytes in buffer
+ * @op: %ITCW_OP_READ for a read operation tcw, %ITCW_OP_WRITE for a write
+ * operation tcw
+ * @intrg: if non-zero, add and initialize an interrogate tcw
+ * @max_tidaws: maximum number of tidaws to be used for data addressing or zero
+ * if no tida is to be used.
+ * @intrg_max_tidaws: maximum number of tidaws to be used for data addressing
+ * by the interrogate tcw, if specified
+ *
+ * Prepare the specified buffer to be used as an incremental tcw, i.e. a
+ * helper data structure that can be used to construct a valid tcw by
+ * successive calls to other helper functions. Note: the buffer needs to be
+ * located below the 2G address limit. The resulting tcw has the following
+ * restrictions:
+ *  - no tccb tidal
+ *  - input/output tidal is contiguous (no ttic)
+ *  - total data should not exceed 4k
+ *  - tcw specifies either read or write operation
+ *
+ * On success, return pointer to the resulting incremental tcw data structure,
+ * ERR_PTR otherwise.
+ */
+struct itcw *itcw_init(void *buffer, size_t size, int op, int intrg,
+		       int max_tidaws, int intrg_max_tidaws)
+{
+	struct itcw *itcw;
+	void *chunk;
+	addr_t start;
+	addr_t end;
+
+	/* Check for 2G limit. */
+	start = (addr_t) buffer;
+	end = start + size;
+	if (end > (1 << 31))
+		return ERR_PTR(-EINVAL);
+	memset(buffer, 0, size);
+	/* ITCW. */
+	chunk = fit_chunk(&start, end, sizeof(struct itcw), 1, 0);
+	if (IS_ERR(chunk))
+		return chunk;
+	itcw = chunk;
+	itcw->max_tidaws = max_tidaws;
+	itcw->intrg_max_tidaws = intrg_max_tidaws;
+	/* Main TCW. */
+	chunk = fit_chunk(&start, end, sizeof(struct tcw), 64, 0);
+	if (IS_ERR(chunk))
+		return chunk;
+	itcw->tcw = chunk;
+	tcw_init(itcw->tcw, (op == ITCW_OP_READ) ? 1 : 0,
+		 (op == ITCW_OP_WRITE) ? 1 : 0);
+	/* Interrogate TCW. */
+	if (intrg) {
+		chunk = fit_chunk(&start, end, sizeof(struct tcw), 64, 0);
+		if (IS_ERR(chunk))
+			return chunk;
+		itcw->intrg_tcw = chunk;
+		tcw_init(itcw->intrg_tcw, 1, 0);
+		tcw_set_intrg(itcw->tcw, itcw->intrg_tcw);
+	}
+	/* Data TIDAL. */
+	if (max_tidaws > 0) {
+		chunk = fit_chunk(&start, end, sizeof(struct tidaw) *
+				  max_tidaws, 16, 1);
+		if (IS_ERR(chunk))
+			return chunk;
+		tcw_set_data(itcw->tcw, chunk, 1);
+	}
+	/* Interrogate data TIDAL. */
+	if (intrg && (intrg_max_tidaws > 0)) {
+		chunk = fit_chunk(&start, end, sizeof(struct tidaw) *
+				  intrg_max_tidaws, 16, 1);
+		if (IS_ERR(chunk))
+			return chunk;
+		tcw_set_data(itcw->intrg_tcw, chunk, 1);
+	}
+	/* TSB. */
+	chunk = fit_chunk(&start, end, sizeof(struct tsb), 8, 0);
+	if (IS_ERR(chunk))
+		return chunk;
+	tsb_init(chunk);
+	tcw_set_tsb(itcw->tcw, chunk);
+	/* Interrogate TSB. */
+	if (intrg) {
+		chunk = fit_chunk(&start, end, sizeof(struct tsb), 8, 0);
+		if (IS_ERR(chunk))
+			return chunk;
+		tsb_init(chunk);
+		tcw_set_tsb(itcw->intrg_tcw, chunk);
+	}
+	/* TCCB. */
+	chunk = fit_chunk(&start, end, TCCB_MAX_SIZE, 8, 0);
+	if (IS_ERR(chunk))
+		return chunk;
+	tccb_init(chunk, TCCB_MAX_SIZE, TCCB_SAC_DEFAULT);
+	tcw_set_tccb(itcw->tcw, chunk);
+	/* Interrogate TCCB. */
+	if (intrg) {
+		chunk = fit_chunk(&start, end, TCCB_MAX_SIZE, 8, 0);
+		if (IS_ERR(chunk))
+			return chunk;
+		tccb_init(chunk, TCCB_MAX_SIZE, TCCB_SAC_INTRG);
+		tcw_set_tccb(itcw->intrg_tcw, chunk);
+		tccb_add_dcw(chunk, TCCB_MAX_SIZE, DCW_CMD_INTRG, 0, NULL,
+			     sizeof(struct dcw_intrg_data), 0);
+		tcw_finalize(itcw->intrg_tcw, 0);
+	}
+	return itcw;
+}
+EXPORT_SYMBOL(itcw_init);
+
+/**
+ * itcw_add_dcw - add a dcw to the itcw
+ * @itcw: address of the itcw
+ * @cmd: the dcw command
+ * @flags: flags for the dcw
+ * @cd: address of control data for this dcw or NULL if none is required
+ * @cd_count: number of control data bytes for this dcw
+ * @count: number of data bytes for this dcw
+ *
+ * Add a new dcw to the specified itcw by writing the dcw information specified
+ * by @cmd, @flags, @cd, @cd_count and @count to the tca of the tccb. Return
+ * a pointer to the newly added dcw on success or -%ENOSPC if the new dcw
+ * would exceed the available space.
+ *
+ * Note: the tcal field of the tccb header will be updated to reflect added
+ * content.
+ */
+struct dcw *itcw_add_dcw(struct itcw *itcw, u8 cmd, u8 flags, void *cd,
+			 u8 cd_count, u32 count)
+{
+	return tccb_add_dcw(tcw_get_tccb(itcw->tcw), TCCB_MAX_SIZE, cmd,
+			    flags, cd, cd_count, count);
+}
+EXPORT_SYMBOL(itcw_add_dcw);
+
+/**
+ * itcw_add_tidaw - add a tidaw to the itcw
+ * @itcw: address of the itcw
+ * @flags: flags for the new tidaw
+ * @addr: address value for the new tidaw
+ * @count: count value for the new tidaw
+ *
+ * Add a new tidaw to the input/output data tidaw-list of the specified itcw
+ * (depending on the value of the r-flag and w-flag). Return a pointer to
+ * the new tidaw on success or -%ENOSPC if the new tidaw would exceed the
+ * available space.
+ *
+ * Note: the tidaw-list is assumed to be contiguous with no ttics. The
+ * last-tidaw flag for the last tidaw in the list will be set by itcw_finalize.
+ */
+struct tidaw *itcw_add_tidaw(struct itcw *itcw, u8 flags, void *addr, u32 count)
+{
+	if (itcw->num_tidaws >= itcw->max_tidaws)
+		return ERR_PTR(-ENOSPC);
+	return tcw_add_tidaw(itcw->tcw, itcw->num_tidaws++, flags, addr, count);
+}
+EXPORT_SYMBOL(itcw_add_tidaw);
+
+/**
+ * itcw_set_data - set data address and tida flag of the itcw
+ * @itcw: address of the itcw
+ * @addr: the data address
+ * @use_tidal: zero of the data address specifies a contiguous block of data,
+ * non-zero if it specifies a list if tidaws.
+ *
+ * Set the input/output data address of the itcw (depending on the value of the
+ * r-flag and w-flag). If @use_tidal is non-zero, the corresponding tida flag
+ * is set as well.
+ */
+void itcw_set_data(struct itcw *itcw, void *addr, int use_tidal)
+{
+	tcw_set_data(itcw->tcw, addr, use_tidal);
+}
+EXPORT_SYMBOL(itcw_set_data);
+
+/**
+ * itcw_finalize - calculate length and count fields of the itcw
+ * @itcw: address of the itcw
+ *
+ * Calculate tcw input-/output-count and tccbl fields and add a tcat the tccb.
+ * In case input- or output-tida is used, the tidaw-list must be stored in
+ * continuous storage (no ttic). The tcal field in the tccb must be
+ * up-to-date.
+ */
+void itcw_finalize(struct itcw *itcw)
+{
+	tcw_finalize(itcw->tcw, itcw->num_tidaws);
+}
+EXPORT_SYMBOL(itcw_finalize);
Index: quilt-2.6/drivers/s390/cio/Makefile
===================================================================
--- quilt-2.6.orig/drivers/s390/cio/Makefile
+++ quilt-2.6/drivers/s390/cio/Makefile
@@ -2,7 +2,8 @@
 # Makefile for the S/390 common i/o drivers
 #
 
-obj-y += airq.o blacklist.o chsc.o cio.o css.o chp.o idset.o scsw.o fcx.o
+obj-y += airq.o blacklist.o chsc.o cio.o css.o chp.o idset.o scsw.o fcx.o \
+	 itcw.o
 ccw_device-objs += device.o device_fsm.o device_ops.o
 ccw_device-objs += device_id.o device_pgid.o device_status.o
 obj-y += ccw_device.o cmf.o
Index: quilt-2.6/include/asm-s390/itcw.h
===================================================================
--- /dev/null
+++ quilt-2.6/include/asm-s390/itcw.h
@@ -0,0 +1,30 @@
+/*
+ *  Functions for incremental construction of fcx enabled I/O control blocks.
+ *
+ *    Copyright IBM Corp. 2008
+ *    Author(s): Peter Oberparleiter <peter.oberparleiter@xxxxxxxxxx>
+ */
+
+#ifndef _ASM_S390_ITCW_H
+#define _ASM_S390_ITCW_H _ASM_S390_ITCW_H
+
+#include <linux/types.h>
+#include <asm/fcx.h>
+
+#define ITCW_OP_READ	0
+#define ITCW_OP_WRITE	1
+
+struct itcw;
+
+struct tcw *itcw_get_tcw(struct itcw *itcw);
+size_t itcw_calc_size(int intrg, int max_tidaws, int intrg_max_tidaws);
+struct itcw *itcw_init(void *buffer, size_t size, int op, int intrg,
+		       int max_tidaws, int intrg_max_tidaws);
+struct dcw *itcw_add_dcw(struct itcw *itcw, u8 cmd, u8 flags, void *cd,
+			 u8 cd_count, u32 count);
+struct tidaw *itcw_add_tidaw(struct itcw *itcw, u8 flags, void *addr,
+			     u32 count);
+void itcw_set_data(struct itcw *itcw, void *addr, int use_tidal);
+void itcw_finalize(struct itcw *itcw);
+
+#endif /* _ASM_S390_ITCW_H */

-- 
blue skies,
   Martin.

"Reality continues to ruin my life." - Calvin.

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