spi: Add function to allocate a new SPI slave

At present it is difficult to extend the SPI structure since all
drivers allocate it themselves, and few of them zero all fields. Add
a new function spi_alloc_slave() which can be used by SPI drivers
to perform this allocation, and thus ensure that all drivers can
better cope with SPI structure changes.

Signed-off-by: Simon Glass <sjg@chromium.org>

drivers/spi/Makefile

@@ -25,6 +25,9 @@ include $(TOPDIR)/config.mk
 
 LIB	:= $(obj)libspi.o
 
+# There are many options which enable SPI, so make this library available
+COBJS-y += spi.o
+
 COBJS-$(CONFIG_ALTERA_SPI) += altera_spi.o
 COBJS-$(CONFIG_ANDES_SPI) += andes_spi.o
 COBJS-$(CONFIG_ARMADA100_SPI) += armada100_spi.o

drivers/spi/spi.c

@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2011 The Chromium OS Authors.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but without any warranty; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#include <common.h>
+#include <malloc.h>
+#include <spi.h>
+
+void *spi_do_alloc_slave(int offset, int size, unsigned int bus,
+			 unsigned int cs)
+{
+	struct spi_slave *slave;
+	void *ptr;
+
+	ptr = malloc(size);
+	if (ptr) {
+		memset(ptr, '\0', size);
+		slave = (struct spi_slave *)(ptr + offset);
+		slave->bus = bus;
+		slave->cs = cs;
+	}
+
+	return ptr;
+}

include/spi.h

@@ -62,6 +62,47 @@ struct spi_slave {
  */
 void spi_init(void);
 
+/**
+ * spi_do_alloc_slave - Allocate a new SPI slave (internal)
+ *
+ * Allocate and zero all fields in the spi slave, and set the bus/chip
+ * select. Use the helper macro spi_alloc_slave() to call this.
+ *
+ * @offset: Offset of struct spi_slave within slave structure
+ * @size: Size of slave structure
+ * @bus: Bus ID of the slave chip.
+ * @cs: Chip select ID of the slave chip on the specified bus.
+ */
+void *spi_do_alloc_slave(int offset, int size, unsigned int bus,
+			 unsigned int cs);
+
+/**
+ * spi_alloc_slave - Allocate a new SPI slave
+ *
+ * Allocate and zero all fields in the spi slave, and set the bus/chip
+ * select.
+ *
+ * @_struct: Name of structure to allocate (e.g. struct tegra_spi). This
+ *	structure must contain a member 'struct spi_slave *slave'.
+ * @bus: Bus ID of the slave chip.
+ * @cs: Chip select ID of the slave chip on the specified bus.
+ */
+#define spi_alloc_slave(_struct, bus, cs) \
+	spi_do_alloc_slave(offsetof(_struct, slave), \
+			    sizeof(_struct), bus, cs)
+
+/**
+ * spi_alloc_slave_base - Allocate a new SPI slave with no private data
+ *
+ * Allocate and zero all fields in the spi slave, and set the bus/chip
+ * select.
+ *
+ * @bus: Bus ID of the slave chip.
+ * @cs: Chip select ID of the slave chip on the specified bus.
+ */
+#define spi_alloc_slave_base(bus, cs) \
+	spi_do_alloc_slave(0, sizeof(struct spi_slave), bus, cs)
+
 /*-----------------------------------------------------------------------
  * Set up communications parameters for a SPI slave.
  *