gpio.c: new subsystem

62202f53 · Alessandro Rubini · d57aed07 · 62202f53 · 62202f53 · 62202f53
Commit 62202f53 authored Apr 17, 2012 by Alessandro Rubini
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Makefile Makefile +1 -1

fd-core.c fd-core.c +1 -0

fine-delay.h fine-delay.h +16 -0

gpio.c gpio.c +100 -0

No files found.
--- a/Makefile
+++ b/Makefile
@@ -10,7 +10,7 @@ ccflags-y += -DDEBUG # temporary
 obj-m := spec-fine-delay.o

 spec-fine-delay-objs	=  fd-zio.o fd-spec.o fd-core.o
-spec-fine-delay-objs	+= onewire.o spi.o i2c.o
+spec-fine-delay-objs	+= onewire.o spi.o i2c.o gpio.o
 spec-fine-delay-objs	+= acam.o pll.o time.o

 all: modules

--- a/fd-core.c
+++ b/fd-core.c
@@ -60,6 +60,7 @@ struct modlist {
 #define M(x) { #x, fd_ ## x ## _init, fd_ ## x ## _exit }
 static struct modlist mods[] = {
 	M(spi),
+	M(gpio),
 	M(pll),
 	//M(w1),
 	//M(i2c),

--- a/fine-delay.h
+++ b/fine-delay.h
@@ -13,6 +13,16 @@ struct spec_fd {
 #define FD_CS_PLL	1	/* AD9516 PLL */
 #define FD_CS_GPIO	2	/* MCP23S17 GPIO */

+/* MCP23S17 register addresses (only ones which are used by the lib) */
+#define FD_MCP_IODIR	0x00
+#define FD_MCP_IPOL	0x01
+#define FD_MCP_IOCON	0x0a
+#define FD_MCP_GPIO	0x12
+#define FD_MCP_OLAT	0x14
+
+#define FD_GPIO_IN	0
+#define FD_GPIO_OUT	1
+
 /* Functions exported by fd-core.c */
 extern int fd_probe(struct spec_dev *dev);
 extern void fd_remove(struct spec_dev *dev);
@@ -27,6 +37,12 @@ extern void fd_spi_exit(struct spec_fd *fd);
 extern int fd_pll_init(struct spec_fd *fd);
 extern void fd_pll_exit(struct spec_fd *fd);

+/* Functions exported by gpio.c */
+extern int fd_gpio_init(struct spec_fd *fd);
+extern void fd_gpio_exit(struct spec_fd *fd);
+extern void fd_gpio_dir(struct spec_fd *fd, int pin, int dir);
+extern void fd_gpio_val(struct spec_fd *fd, int pin, int val);
+
 /* Functions exported by fd-zio.c */
 extern int fd_zio_register(void);
 extern void fd_zio_unregister(void);

--- a/gpio.c
+++ b/gpio.c
+/*
+ * SPI access to fine-delay internals
+ *
+ * Copyright (C) 2012 CERN (www.cern.ch)
+ * Author: Tomasz Wlostowski <tomasz.wlostowski@cern.ch>
+ * Author: Alessandro Rubini <rubini@gnudd.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * version 2 as published by the Free Software Foundation or, at your
+ * option, any later version.
+ */
+
+#include <linux/io.h>
+#include "fine-delay.h"
+
+static int gpio_writel(struct spec_fd *fd, int val, int reg)
+{
+	return fd_spi_xfer(fd, FD_CS_GPIO, 24,
+			   0x4e0000 | (reg << 8) | val, NULL);
+}
+
+static int gpio_readl(struct spec_fd *fd, int reg)
+{
+	uint32_t ret;
+	int err;
+
+	err = fd_spi_xfer(fd, FD_CS_GPIO, 24,
+			  0x4f0000 | (reg << 8), &ret);
+	if (err < 0)
+		return err;
+	return ret & 0xff;
+}
+
+void fd_gpio_dir(struct spec_fd *fd, int mask, int dir)
+{
+	int addr, val;
+
+	/* if mask is bits 8..15 use the next address */
+	addr = FD_MCP_IODIR;
+	if (mask & 0xff00) {
+		mask >>= 8;
+		addr++;
+	}
+	val = gpio_readl(fd, addr) & ~mask;
+	if (dir == FD_GPIO_IN)
+		val |= mask;
+	gpio_writel(fd, val, addr);
+}
+
+void fd_gpio_val(struct spec_fd *fd, int mask, int values)
+{
+	int addr, reg;
+
+	/* if mask is bits 8..15 use the next address */
+	addr = FD_MCP_OLAT;
+	if (mask & 0xff00) {
+		mask >>= 8;
+		values >>= 8;
+		addr++;
+	}
+	reg = gpio_readl(fd, addr) & ~mask;
+	gpio_writel(fd, reg | values, addr);
+}
+
+
+int fd_gpio_init(struct spec_fd *fd)
+{
+	int i, val;
+
+	pr_debug("%s\n",__func__);
+	if (gpio_writel(fd, 0x00, FD_MCP_IOCON) < 0)
+		goto out;
+
+	/* Try to read and write a register to test the SPI connection */
+	for (val = 0xaa; val >= 0; val -= 0x11) {
+		if (gpio_writel(fd, val, FD_MCP_IPOL) < 0)
+			goto out;
+		i = gpio_readl(fd, FD_MCP_IPOL);
+		if (i < 0)
+			goto out;
+		if (i != val) {
+			pr_err("%s: Error in GPIO communication\n",
+			       KBUILD_MODNAME);
+			pr_err("   (got 0x%x, expected 0x%x)\n", i, val);
+			return -EIO;
+		}
+	}
+	/* last time we wrote 0, ok */
+	return 0;
+out:
+	pr_err("%s: Error in SPI communication\n", KBUILD_MODNAME);
+	return -EIO;
+}
+
+void fd_gpio_exit(struct spec_fd *fd)
+{
+	/* nothing to do */
+}
+