[U-Boot] [PATCH V4] Davinci: add a pin multiplexer configuration API

[Nick Thompson]

Davinci: add a pin multiplexer configuration API.

Creates a method allowing pin settings to be logically grouped into data
structure arrays and provides an API to configure the pinmux settings to
enable the relevant pin functions.

Signed-off-by: Nick Thompson <nick.thompson at gefanuc.com>
---
Applies to: u-boot-ti

Changes from last patch:
	Make example match current usage (in DA8xx code, to follow)
	Error check all pin settings before applying any changes
	Type correction

The number of mux fields per register and the width of the fields needs to
be set per SoC. The initial settings are appropriate for at least DA8xx
devices. These should be modified in misc.h to support other devices as
required.

 board/davinci/common/misc.c |   48 ++++++++++++++++++++++++++++++++++++++++++-
 board/davinci/common/misc.h |   12 ++++++++++
 2 files changed, 59 insertions(+), 1 deletions(-)

diff --git a/board/davinci/common/misc.c b/board/davinci/common/misc.c
index ffdc20b..9fab76f 100644
--- a/board/davinci/common/misc.c
+++ b/board/davinci/common/misc.c
@@ -1,6 +1,7 @@
 /*
  * Miscelaneous DaVinci functions.
  *
+ * Copyright (C) 2009 Nick Thompson, GE Fanuc Ltd, <nick.thompson at gefanuc.com>
  * Copyright (C) 2007 Sergey Kubushyn <ksi at koi8.net>
  * Copyright (C) 2008 Lyrtech <www.lyrtech.com>
  * Copyright (C) 2004 Texas Instruments.
@@ -27,7 +28,8 @@
 #include <i2c.h>
 #include <net.h>
 #include <asm/arch/hardware.h>
-
+#include <asm/io.h>
+#include "misc.h"
 
 DECLARE_GLOBAL_DATA_PTR;
 
@@ -109,3 +111,47 @@ void dv_configure_mac_address(uint8_t *rom_enetaddr)
 }
 
 #endif	/* DAVINCI_EMAC */
+
+/*
+ * Change the setting of a pin multiplexer field.
+ *
+ * Takes an array of pinmux settings similar to:
+ *
+ * struct pinmux_config uart_pins[] = {
+ *	{ &davinci_syscfg_regs->pinmux[8], 2, 7 },
+ *	{ &davinci_syscfg_regs->pinmux[9], 2, 0 }
+ * };
+ *
+ * Stepping through the array, each pinmux[n] register has the given value
+ * set in the pin mux field specified.
+ *
+ * The number of pins in the array must be passed (ARRAY_SIZE can provide
+ * this value conveniently).
+ *
+ * Returns 0 if all field numbers and values are in the correct range,
+ * else returns -1.
+ */
+int davinci_configure_pin_mux(const struct pinmux_config *pins,
+			      const int n_pins)
+{
+	int i;
+
+	/* check for invalid pinmux values */
+	for (i = 0; i < n_pins; i++) {
+		if (pins[i].field >= PIN_MUX_NUM_FIELDS ||
+		    (pins[i].value & ~PIN_MUX_FIELD_MASK) != 0)
+			return -1;
+	}
+
+	/* configure the pinmuxes */
+	for (i = 0; i < n_pins; i++) {
+		const int offset = pins[i].field * PIN_MUX_FIELD_SIZE;
+		const unsigned int value = pins[i].value << offset;
+		const unsigned int mask = PIN_MUX_FIELD_MASK << offset;
+		const dv_reg *mux = pins[i].mux;
+
+		writel(value | (readl(mux) & (~mask)), mux);
+	}
+
+	return 0;
+}
diff --git a/board/davinci/common/misc.h b/board/davinci/common/misc.h
index dc3cc41..f6d8b1b 100644
--- a/board/davinci/common/misc.h
+++ b/board/davinci/common/misc.h
@@ -22,8 +22,20 @@
 #ifndef __MISC_H
 #define __MISC_H
 
+/* pin muxer definitions */
+#define PIN_MUX_NUM_FIELDS	8	/* Per register */
+#define PIN_MUX_FIELD_SIZE	4	/* n in bits */
+#define PIN_MUX_FIELD_MASK	((1 << PIN_MUX_FIELD_SIZE) - 1)
+
+/* pin definition */
+struct pinmux_config {
+	dv_reg		*mux;		/* Address of mux register */
+	unsigned char	value;		/* Value to set in field */
+	unsigned char	field;		/* field number */
+};
 
 int dvevm_read_mac_address(uint8_t *buf);
 void dv_configure_mac_address(uint8_t *rom_enetaddr);
+int davinci_configure_pin_mux(const struct pinmux_config *pins, int n_pins);
 
 #endif /* __MISC_H */