Patchwork [U-Boot,v4,3/4] mpc85xx: Add inline GPIO acessor functions

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Submitter Kyle Moffett
Date Feb. 23, 2011, 7:28 p.m.
Message ID <1298489327-12361-3-git-send-email-Kyle.D.Moffett@boeing.com>
Download mbox | patch
Permalink /patch/84225/
State Superseded
Headers show

Comments

Kyle Moffett - Feb. 23, 2011, 7:28 p.m.
To ease the implementation of other MPC85xx board ports, several common
GPIO helpers are added to <asm/mpc85xx_gpio.h>.

Since each of these compiles to no more than 4-5 instructions it would
be very inefficient to call them out of line, therefore we put them
entirely in the header file.

The HWW-1U-1A board port which these were written for strongly prefers
to set multiple GPIOs as a single batch operation, so the API is
designed around that basis.

To assist other board ports, a small set of wrappers are used which
provides a standard gpio_request() interface around the MPC85xx-specific
functions.  This can be enabled with CONFIG_MPC85XX_GENERIC_GPIO

Signed-off-by: Kyle Moffett <Kyle.D.Moffett@boeing.com>
Cc: Andy Fleming <afleming@gmail.com>
Cc: Kumar Gala <kumar.gala@freescale.com>
Cc: Peter Tyser <ptyser@xes-inc.com>
---
Changelog:
  v2: Moved the inline functions to a non-board-specific header
  v3: Added generic Linux-standard GPIO wrappers
  v4: Improved comments and fixed minor bugs in the wrapper functions

 arch/powerpc/include/asm/mpc85xx_gpio.h |  120 +++++++++++++++++++++++++++++++
 1 files changed, 120 insertions(+), 0 deletions(-)
 create mode 100644 arch/powerpc/include/asm/mpc85xx_gpio.h

Patch

diff --git a/arch/powerpc/include/asm/mpc85xx_gpio.h b/arch/powerpc/include/asm/mpc85xx_gpio.h
new file mode 100644
index 0000000..ad54b4e
--- /dev/null
+++ b/arch/powerpc/include/asm/mpc85xx_gpio.h
@@ -0,0 +1,120 @@ 
+/*
+ * Copyright 2010 eXMeritus, A Boeing Company
+ *
+ * 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 <asm/immap_85xx.h>
+
+/*
+ * The following internal functions are an MPC85XX-specific GPIO API which
+ * allows setting and querying multiple GPIOs in a single operation.
+ *
+ * All of these look relatively large, but the arguments are almost always
+ * constants, so they compile down to just a few instructions and a
+ * memory-mapped IO operation or two.
+ */
+static inline void mpc85xx_gpio_set(unsigned int mask,
+		unsigned int dir, unsigned int val)
+{
+	ccsr_gpio_t *gpio = (void *)(CONFIG_SYS_MPC85xx_GPIO_ADDR + 0xc00);
+
+	/* First mask off the unwanted parts of "dir" and "val" */
+	dir &= mask;
+	val &= mask;
+
+	/* Now read in the values we're supposed to preserve */
+	dir |= (in_be32(&gpio->gpdir) & ~mask);
+	val |= (in_be32(&gpio->gpdat) & ~mask);
+
+	/*
+	 * Poke the new output values first, then set the direction.  This
+	 * helps to avoid transient data when switching from input to output
+	 * and vice versa.
+	 */
+	out_be32(&gpio->gpdat, val);
+	out_be32(&gpio->gpdir, dir);
+}
+
+static inline void mpc85xx_gpio_set_in(unsigned int gpios)
+{
+	mpc85xx_gpio_set(gpios, 0x00000000, 0x00000000);
+}
+
+static inline void mpc85xx_gpio_set_low(unsigned int gpios)
+{
+	mpc85xx_gpio_set(gpios, 0xFFFFFFFF, 0x00000000);
+}
+
+static inline void mpc85xx_gpio_set_high(unsigned int gpios)
+{
+	mpc85xx_gpio_set(gpios, 0xFFFFFFFF, 0xFFFFFFFF);
+}
+
+static inline unsigned int mpc85xx_gpio_get(unsigned int mask)
+{
+	ccsr_gpio_t *gpio = (void *)(CONFIG_SYS_MPC85xx_GPIO_ADDR + 0xc00);
+
+	/* Read the requested values */
+	return in_be32(&gpio->gpdat) & mask;
+}
+
+/*
+ * These implement the generic Linux GPIO API on top of the other functions
+ * in this header.
+ */
+#ifdef CONFIG_MPC85XX_GENERIC_GPIO
+static inline int gpio_request(unsigned gpio, const char *label)
+{
+	/* Compatibility shim */
+	return 0;
+}
+
+static inline void gpio_free(unsigned gpio)
+{
+	/* Compatibility shim */
+}
+
+static inline int gpio_direction_input(unsigned gpio)
+{
+	mpc85xx_gpio_set_in(1U << gpio);
+	return 0;
+}
+
+static inline int gpio_direction_output(unsigned gpio, int value)
+{
+	mpc85xx_gpio_set_low(1U << gpio);
+	return 0;
+}
+
+static inline int gpio_get_value(unsigned gpio)
+{
+	return !!mpc85xx_gpio_get(1U << gpio)
+}
+
+static inline void gpio_set_value(unsigned gpio, int value)
+{
+	if (value)
+		mpc85xx_gpio_set_high(1U << gpio);
+	else
+		mpc85xx_gpio_set_low(1U << gpio);
+}
+
+static inline int gpio_is_valid(int gpio)
+{
+	return (gpio >= 0) && (gpio < 32);
+}
+#endif /* CONFIG_MPC85XX_GENERIC_GPIO */