diff mbox series

[2/3] x86: Add basic support for the Congatec CGEB BIOS interface

Message ID 20240718011504.4106163-3-mstrodl@csh.rit.edu (mailing list archive)
State New
Headers show
Series Add support for Congatec CGEB BIOS interface | expand

Commit Message

Mary Strodl July 18, 2024, 1:15 a.m. UTC
From: Sascha Hauer <s.hauer@pengutronix.de>

The Congatec CGEB is a BIOS interface found on some Congatec x86
modules. It provides access to on board peripherals like I2C busses
and watchdogs. This driver contains the basic support for accessing
the CGEB interface and registers the child devices.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Signed-off-by: Mary Strodl <mstrodl@csh.rit.edu>
---
 drivers/mfd/Kconfig               |  10 +
 drivers/mfd/Makefile              |   1 +
 drivers/mfd/congatec-cgeb.c       | 620 ++++++++++++++++++++++++++++++
 include/linux/mfd/congatec-cgeb.h | 105 +++++
 4 files changed, 736 insertions(+)
 create mode 100644 drivers/mfd/congatec-cgeb.c
 create mode 100644 include/linux/mfd/congatec-cgeb.h

Comments

kernel test robot July 18, 2024, 3:56 a.m. UTC | #1
Hi Mary,

kernel test robot noticed the following build warnings:

[auto build test WARNING on lee-mfd/for-mfd-next]
[also build test WARNING on lee-mfd/for-mfd-fixes akpm-mm/mm-everything andi-shyti/i2c/i2c-host linus/master v6.10 next-20240717]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Mary-Strodl/mm-vmalloc-export-__vmalloc_node_range/20240718-091816
base:   https://git.kernel.org/pub/scm/linux/kernel/git/lee/mfd.git for-mfd-next
patch link:    https://lore.kernel.org/r/20240718011504.4106163-3-mstrodl%40csh.rit.edu
patch subject: [PATCH 2/3] x86: Add basic support for the Congatec CGEB BIOS interface
reproduce: (https://download.01.org/0day-ci/archive/20240718/202407181147.SJ9mOE8q-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202407181147.SJ9mOE8q-lkp@intel.com/

versioncheck warnings: (new ones prefixed by >>)
   INFO PATH=/opt/cross/rustc-1.78.0-bindgen-0.65.1/cargo/bin:/opt/cross/clang-18/bin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
   /usr/bin/timeout -k 100 3h /usr/bin/make KCFLAGS= -Wtautological-compare -Wno-error=return-type -Wreturn-type -Wcast-function-type -funsigned-char -Wundef -fstrict-flex-arrays=3 -Wformat-overflow -Wformat-truncation -Wenum-conversion W=1 --keep-going LLVM=1 -j32 ARCH=x86_64 versioncheck
   find ./* \( -name SCCS -o -name BitKeeper -o -name .svn -o -name CVS -o -name .pc -o -name .hg -o -name .git \) -prune -o \
   	-name '*.[hcS]' -type f -print | sort \
   	| xargs perl -w ./scripts/checkversion.pl
   ./drivers/accessibility/speakup/genmap.c: 13 linux/version.h not needed.
   ./drivers/accessibility/speakup/makemapdata.c: 13 linux/version.h not needed.
>> ./drivers/mfd/congatec-cgeb.c: 25 linux/version.h not needed.
   ./drivers/staging/media/atomisp/include/linux/atomisp.h: 23 linux/version.h not needed.
   ./samples/bpf/spintest.bpf.c: 8 linux/version.h not needed.
   ./samples/trace_events/trace_custom_sched.c: 11 linux/version.h not needed.
   ./sound/soc/codecs/cs42l42.c: 14 linux/version.h not needed.
   ./tools/lib/bpf/bpf_helpers.h: 423: need linux/version.h
   ./tools/testing/selftests/bpf/progs/dev_cgroup.c: 9 linux/version.h not needed.
   ./tools/testing/selftests/bpf/progs/netcnt_prog.c: 3 linux/version.h not needed.
   ./tools/testing/selftests/bpf/progs/test_map_lock.c: 4 linux/version.h not needed.
   ./tools/testing/selftests/bpf/progs/test_send_signal_kern.c: 4 linux/version.h not needed.
   ./tools/testing/selftests/bpf/progs/test_spin_lock.c: 4 linux/version.h not needed.
   ./tools/testing/selftests/bpf/progs/test_tcp_estats.c: 37 linux/version.h not needed.
   ./tools/testing/selftests/wireguard/qemu/init.c: 27 linux/version.h not needed.
kernel test robot July 18, 2024, 2:01 p.m. UTC | #2
Hi Mary,

kernel test robot noticed the following build warnings:

[auto build test WARNING on lee-mfd/for-mfd-next]
[also build test WARNING on lee-mfd/for-mfd-fixes akpm-mm/mm-everything andi-shyti/i2c/i2c-host linus/master v6.10 next-20240718]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Mary-Strodl/mm-vmalloc-export-__vmalloc_node_range/20240718-091816
base:   https://git.kernel.org/pub/scm/linux/kernel/git/lee/mfd.git for-mfd-next
patch link:    https://lore.kernel.org/r/20240718011504.4106163-3-mstrodl%40csh.rit.edu
patch subject: [PATCH 2/3] x86: Add basic support for the Congatec CGEB BIOS interface
config: i386-allmodconfig (https://download.01.org/0day-ci/archive/20240718/202407182128.dYt4Ud4g-lkp@intel.com/config)
compiler: gcc-13 (Ubuntu 13.2.0-4ubuntu3) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240718/202407182128.dYt4Ud4g-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202407182128.dYt4Ud4g-lkp@intel.com/

All warnings (new ones prefixed by >>):

   drivers/mfd/congatec-cgeb.c: In function 'cgeb_map_memory':
>> drivers/mfd/congatec-cgeb.c:360:52: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
     360 |                                 ioremap_cache((u32)(resource_size_t)pmme->phys,
         |                                                    ^


vim +360 drivers/mfd/congatec-cgeb.c

   334	
   335	static int cgeb_map_memory(struct cgeb_board_data *board)
   336	{
   337		struct cgeb_map_mem_list *pmm;
   338		struct cgeb_map_mem *pmme;
   339		int i;
   340		int ret;
   341	
   342		ret = cgeb_call_simple(board, CgebMapGetMem, 0, (void *)&board->map_mem,
   343				NULL);
   344		if (ret)
   345			return ret;
   346		if (!board->map_mem)
   347			return 0;
   348	
   349		pmm = board->map_mem;
   350		pmme = pmm->entries;
   351	
   352		pr_debug("CGEB: Memory Map with %d entries\n", pmm->count);
   353	
   354		for (i = 0; i < pmm->count; i++, pmme++) {
   355			pr_debug("CGEB: Memory map entry phys=%px, size=%08x\n",
   356					pmme->phys, pmme->size);
   357			if (pmme->phys && pmme->size) {
   358				/* We only want to look at the lower 32 bits */
   359				pmme->virt.off =
 > 360					ioremap_cache((u32)(resource_size_t)pmme->phys,
   361						pmme->size);
   362				if (!pmme->virt.off)
   363					return -ENOMEM;
   364			 } else {
   365				pmme->virt.off = 0;
   366			}
   367	
   368			pmme->virt.seg = (pmme->virt.off) ? board->ds : 0;
   369	
   370			pr_debug("CGEB:   Map phys %p, size %08x, virt %04x:%p\n",
   371				pmme->phys, pmme->size, pmme->virt.seg,
   372				pmme->virt.off);
   373		}
   374	
   375		return cgeb_call_simple(board, CgebMapChanged, 0, NULL, NULL);
   376	}
   377
diff mbox series

Patch

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 266b4f54af60..fa06a9dc34f9 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -1206,6 +1206,16 @@  config MFD_RT5120
 	  is targeted at providing the CPU voltage, memory, I/O and peripheral
 	  power rails in home entertainment devices.
 
+config MFD_CONGATEC_CGEB
+	tristate "Support for the Congatec CGEB BIOS interface"
+	depends on X86
+	help
+	  The Congatec CGEB BIOS interface provides access to onboard
+	  peripherals like I2C busses and watchdogs. additional drivers must be
+	  enabled in order to use the functionality of the device.
+	  Say y or m here if you are using a congatec module with CGEB interface,
+	  otherwise say n.
+
 config MFD_RC5T583
 	bool "Ricoh RC5T583 Power Management system device"
 	depends on I2C=y
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index c66f07edcd0e..38f31841ac88 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -217,6 +217,7 @@  obj-$(CONFIG_MFD_INTEL_LPSS)	+= intel-lpss.o
 obj-$(CONFIG_MFD_INTEL_LPSS_PCI)	+= intel-lpss-pci.o
 obj-$(CONFIG_MFD_INTEL_LPSS_ACPI)	+= intel-lpss-acpi.o
 obj-$(CONFIG_MFD_INTEL_PMC_BXT)	+= intel_pmc_bxt.o
+obj-$(CONFIG_MFD_CONGATEC_CGEB)	+= congatec-cgeb.o
 obj-$(CONFIG_MFD_PALMAS)	+= palmas.o
 obj-$(CONFIG_MFD_VIPERBOARD)    += viperboard.o
 obj-$(CONFIG_MFD_NTXEC)		+= ntxec.o
diff --git a/drivers/mfd/congatec-cgeb.c b/drivers/mfd/congatec-cgeb.c
new file mode 100644
index 000000000000..2bae1f42c357
--- /dev/null
+++ b/drivers/mfd/congatec-cgeb.c
@@ -0,0 +1,620 @@ 
+/*
+ * CGEB driver
+ *
+ * (c) 2011 Sascha Hauer, Pengutronix
+ *
+ * Based on code from Congatec AG.
+ *
+ * CGEB is a BIOS interface found on congatech modules. It consists of
+ * code found in the BIOS memory map which is called in a ioctl like
+ * fashion. This file contains the basic driver for this interface
+ * which provides access to the GCEB interface and registers the child
+ * devices like I2C busses and watchdogs.
+ *
+ * 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; version 2 of the License.
+ *
+ * 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.
+ */
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/version.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/io.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/mm.h>
+#include <linux/delay.h>
+#include <linux/platform_device.h>
+#include <linux/mfd/congatec-cgeb.h>
+
+#include <generated/autoconf.h>
+
+#define CGOS_BOARD_MAX_SIZE_ID_STRING 16
+
+#define CGEB_VERSION_MAJOR 1
+
+#define CGEB_GET_VERSION_MAJOR(v) (((unsigned long)(v)) >> 24)
+
+/* CGEB Low Descriptor located in 0xc0000-0xfffff */
+#define CGEB_LD_MAGIC "$CGEBLD$"
+
+#pragma pack(push,4)
+
+struct cgeb_low_desc {
+	char magic[8];          /* descriptor magic string */
+	u16 size;               /* size of this descriptor */
+	u16 reserved;
+	char bios_name[8];      /* BIOS name and revision "ppppRvvv" */
+	u32 hi_desc_phys_addr;  /* phys addr of the high descriptor, can be 0 */
+};
+
+/* CGEB High Descriptor located in 0xfff00000-0xffffffff */
+#ifdef CONFIG_X86_64
+#define CGEB_HD_MAGIC "$CGEBQD$"
+#else
+#define CGEB_HD_MAGIC "$CGEBHD$"
+#endif
+
+struct cgeb_high_desc {
+	char magic[8];          /* descriptor magic string */
+	u16 size;               /* size of this descriptor */
+	u16 reserved;
+	u32 data_size;          /* CGEB data area size */
+	u32 code_size;          /* CGEB code area size */
+	u32 entry_rel;          /* CGEB entry point relative to start */
+};
+
+struct cgeb_far_ptr {
+	void* off;
+	u16 seg;
+	u16 pad;
+};
+
+struct cgeb_fps {
+	u32 size;               /* size of the parameter structure */
+	u32 fct;                /* function number */
+	struct cgeb_far_ptr data;       /* CGEB data area */
+	void* cont;             /* private continuation pointer */
+	void* subfps;           /* private sub function parameter
+				 * structure pointer
+				 */
+	void* subfct;           /* sub function pointer */
+	u32 status;             /* result codes of the function */
+	u32 unit;               /* unit number or type */
+	u32 pars[4];            /* input parameters */
+	u32 rets[2];            /* return parameters */
+	void *iptr;             /* input pointer */
+	void *optr;             /* output pointer */
+};
+
+/* continuation status codes */
+#define CGEB_SUCCESS            0
+#define CGEB_NEXT               1
+#define CGEB_DELAY              2
+#define CGEB_NOIRQS             3
+
+#define CGEB_DBG_STR        0x100
+#define CGEB_DBG_HEX        0x101
+#define CGEB_DBG_DEC        0x102
+
+struct cgeb_map_mem {
+	void* phys;             /* physical address */
+	u32 size;               /* size in bytes */
+	struct cgeb_far_ptr virt;
+};
+
+struct cgeb_map_mem_list {
+	u32 count;              /* number of memory map entries */
+	struct cgeb_map_mem entries[];
+};
+
+struct cgeb_boardinfo {
+	u32 size;
+	u32 flags;
+	u32 classes;
+	u32 primary_class;
+	char board[CGOS_BOARD_MAX_SIZE_ID_STRING];
+	/* optional */
+	char vendor[CGOS_BOARD_MAX_SIZE_ID_STRING];
+};
+
+struct cgeb_i2c_info {
+	u32 size;
+	u32 type;
+	u32 frequency;
+	u32 maxFrequency;
+};
+
+#pragma pack(pop)
+
+/* I2C Types */
+#define CGEB_I2C_TYPE_UNKNOWN 0
+#define CGEB_I2C_TYPE_PRIMARY 1
+#define CGEB_I2C_TYPE_SMB     2
+#define CGEB_I2C_TYPE_DDC     3
+#define CGEB_I2C_TYPE_BC      4
+
+struct cgeb_board_data {
+	void *code;
+	void *data;
+	u16 ds;
+	struct cgeb_map_mem_list *map_mem;
+	struct platform_device **devices;
+	int num_devices;
+
+	#ifdef CONFIG_X86_64
+	void (*entry)(void*, struct cgeb_fps *, struct cgeb_fps *, void*);
+	#else
+	/*
+	 * entry points to a bimodal C style function that expects a far pointer
+	 * to a fps. If cs is 0 then it does a near return, otherwise a far
+	 * return. If we ever need a far return then we must not pass cs at all.
+	 * parameters are removed by the caller.
+	 */
+	void __attribute__((regparm(0)))(*entry)(unsigned short,
+			  struct cgeb_fps *, unsigned short);
+	#endif
+};
+
+static unsigned short get_data_segment(void)
+{
+	unsigned short ret;
+
+#ifdef CONFIG_X86_64
+	ret = 0;
+#else
+	asm volatile("mov %%ds, %0\n"
+			  : "=r"(ret)
+			  :
+			  : "memory"
+	);
+#endif
+
+	return ret;
+}
+
+/*
+ * cgeb_call - invoke CGEB BIOS call.
+ *
+ * @board:     board context data
+ * @p:         CGEB parameters for this call
+ * @fct:       CGEB function code
+ * @return:    0 on success or negative error code on failure.
+ *
+ * Call the CGEB BIOS code with the given parameters.
+ */
+unsigned int cgeb_call(struct cgeb_board_data *board,
+		 struct cgeb_function_parameters *p, cgeb_function_t fct)
+{
+	struct cgeb_fps fps;
+	int i;
+
+	memset(&fps, 0, sizeof(fps));
+
+	fps.size = sizeof(fps);
+	fps.fct = fct;
+	fps.data.off = board->data;
+	fps.data.seg = board->ds;
+	fps.data.pad = 0;
+	fps.status = 0;
+	fps.cont = fps.subfct = fps.subfps = 0;
+	fps.unit = p->unit;
+	for (i = 0; i < 4; i++)
+		fps.pars[i] = p->pars[i];
+	fps.iptr = p->iptr;
+	fps.optr = p->optr;
+
+	while (1) {
+		pr_debug("CGEB: CGEB: ->  size %02x, fct %02x, data %04x:%p, status %08x\n",
+				fps.size, fps.fct, fps.data.seg, fps.data.off,
+				fps.status);
+
+#ifdef CONFIG_X86_64
+		board->entry(NULL, &fps, &fps, NULL);
+#else
+		board->entry(0, &fps, fps.data.seg);
+#endif
+
+		pr_debug("CGEB: CGEB: <-  size %02x, fct %02x, data %04x:%p, status %08x\n",
+				fps.size, fps.fct, fps.data.seg, fps.data.off,
+				fps.status);
+
+		switch (fps.status) {
+		case CGEB_SUCCESS:
+			goto out;
+		case CGEB_NEXT:
+			break;  /* simply call again */
+		case CGEB_NOIRQS:
+			__set_current_state(TASK_INTERRUPTIBLE);
+			schedule_timeout(0);
+			break;
+		case CGEB_DELAY:
+			usleep_range(fps.rets[0], fps.rets[0] + 1000);
+			break;
+		case CGEB_DBG_STR:
+			if (fps.optr)
+				pr_debug("CGEB: %s\n", (char *)fps.optr);
+			break;
+		case CGEB_DBG_HEX:
+			pr_debug("CGEB: 0x%08x\n", fps.rets[0]);
+			break;
+		case CGEB_DBG_DEC:
+			pr_debug("CGEB: %d\n", fps.rets[0]);
+			break;
+
+		default:
+			/* unknown continuation code */
+			return -EINVAL;
+		}
+	}
+out:
+	for (i = 0; i < 2; i++)
+		p->rets[i] = fps.rets[i];
+	p->optr = fps.optr;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(cgeb_call);
+
+/*
+ * cgeb_call_simple - convenience wrapper for cgeb_call
+ *
+ * @board:     board context data
+ * @p:         CGEB parameters for this call
+ * @fct:       CGEB function code
+ * @return:    0 on success or negative error code on failure.
+ *
+ * Call the CGEB BIOS code with the given parameters.
+ */
+int cgeb_call_simple(struct cgeb_board_data *board,
+		 cgeb_function_t fct, u32 unit,
+		 void **optr, u32 *result)
+{
+	struct cgeb_function_parameters p;
+	unsigned int ret;
+
+	memset(&p, 0, sizeof(p));
+	p.unit = unit;
+	p.optr = optr;
+
+	ret = cgeb_call(board, &p, fct);
+	if (optr)
+		*optr = p.optr;
+	if (result)
+		*result = p.rets[0];
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(cgeb_call_simple);
+
+static void *cgeb_find_magic(void *_mem, size_t len, char *magic)
+{
+	u32 magic0 = ((u32 *)magic)[0];
+	u32 magic1 = ((u32 *)magic)[1];
+	int i = 0;
+
+	while (i < len) {
+		u32 *mem = _mem + i;
+
+		if (mem[0] == magic0 && mem[1] == magic1)
+			return mem;
+		i += 16;
+	}
+
+	return NULL;
+}
+
+static void cgeb_unmap_memory(struct cgeb_board_data *board)
+{
+	struct cgeb_map_mem_list *pmm;
+	struct cgeb_map_mem *pmme;
+	unsigned long i;
+
+	if (!board->map_mem)
+		return;
+
+	pmm = board->map_mem;
+	pmme = pmm->entries;
+	for (i = 0; i < pmm->count; i++, pmme++) {
+		if (pmme->virt.off)
+			iounmap((void *)pmme->virt.off);
+		pmme->virt.off = 0;
+		pmme->virt.seg = 0;
+	}
+}
+
+static int cgeb_map_memory(struct cgeb_board_data *board)
+{
+	struct cgeb_map_mem_list *pmm;
+	struct cgeb_map_mem *pmme;
+	int i;
+	int ret;
+
+	ret = cgeb_call_simple(board, CgebMapGetMem, 0, (void *)&board->map_mem,
+			NULL);
+	if (ret)
+		return ret;
+	if (!board->map_mem)
+		return 0;
+
+	pmm = board->map_mem;
+	pmme = pmm->entries;
+
+	pr_debug("CGEB: Memory Map with %d entries\n", pmm->count);
+
+	for (i = 0; i < pmm->count; i++, pmme++) {
+		pr_debug("CGEB: Memory map entry phys=%px, size=%08x\n",
+				pmme->phys, pmme->size);
+		if (pmme->phys && pmme->size) {
+			/* We only want to look at the lower 32 bits */
+			pmme->virt.off =
+				ioremap_cache((u32)(resource_size_t)pmme->phys,
+					pmme->size);
+			if (!pmme->virt.off)
+				return -ENOMEM;
+		 } else {
+			pmme->virt.off = 0;
+		}
+
+		pmme->virt.seg = (pmme->virt.off) ? board->ds : 0;
+
+		pr_debug("CGEB:   Map phys %p, size %08x, virt %04x:%p\n",
+			pmme->phys, pmme->size, pmme->virt.seg,
+			pmme->virt.off);
+	}
+
+	return cgeb_call_simple(board, CgebMapChanged, 0, NULL, NULL);
+}
+
+static struct cgeb_board_data *cgeb_open(resource_size_t base, u32 len)
+{
+	u32 dw;
+	struct cgeb_boardinfo *pbi;
+	struct cgeb_low_desc *low_desc;
+	struct cgeb_high_desc *high_desc = NULL;
+	u32 high_desc_phys;
+	u32 high_desc_len;
+	void __iomem *pcur, *high_desc_virt;
+	int ret;
+
+	struct cgeb_board_data *board;
+
+	board = kzalloc(sizeof(*board), GFP_KERNEL);
+	if (!board)
+		return NULL;
+
+	pcur = ioremap_cache(base, len);
+	if (!pcur)
+		goto err_kfree;
+
+	/* look for the CGEB descriptor */
+	low_desc = cgeb_find_magic(pcur, len, CGEB_LD_MAGIC);
+	if (!low_desc)
+		goto err_kfree;
+
+	pr_debug("CGEB: Found CGEB_LD_MAGIC\n");
+
+	if (low_desc->size < sizeof(struct cgeb_low_desc) - sizeof(long))
+		goto err_kfree;
+
+	if (low_desc->size >= sizeof(struct cgeb_low_desc)
+			&& low_desc->hi_desc_phys_addr)
+		high_desc_phys = low_desc->hi_desc_phys_addr;
+	else
+		high_desc_phys = 0xfff00000;
+
+	high_desc_len = (unsigned int) -(int)high_desc_phys;
+
+	pr_debug("CGEB: Looking for CGEB hi desc between phys 0x%x and 0x%x\n",
+		high_desc_phys, -1);
+
+	high_desc_virt = ioremap_cache(high_desc_phys, high_desc_len);
+	if (!high_desc_virt)
+		goto err_kfree;
+
+	pr_debug("CGEB: Looking for CGEB hi desc between virt 0x%p and 0x%p\n",
+		high_desc_virt, high_desc_virt + high_desc_len - 1);
+
+	high_desc = cgeb_find_magic(high_desc_virt, high_desc_len,
+					CGEB_HD_MAGIC);
+	if (!high_desc)
+		goto err_iounmap;
+
+	pr_debug("CGEB: Found CGEB_HD_MAGIC\n");
+
+	if (high_desc->size < sizeof(struct cgeb_high_desc))
+		goto err_iounmap;
+
+	pr_debug("CGEB: data_size %u, code_size %u, entry_rel %u\n",
+		high_desc->data_size, high_desc->code_size, high_desc->entry_rel);
+
+	board->code = __vmalloc_node_range(high_desc->code_size, 1,
+					   VMALLOC_START, VMALLOC_END,
+					   GFP_KERNEL, PAGE_KERNEL_EXEC,
+					   (VM_WRITE | VM_EXEC), NUMA_NO_NODE,
+					   __builtin_return_address(0));
+	if (!board->code)
+		goto err_iounmap;
+
+	memcpy(board->code, high_desc, high_desc->code_size);
+
+	high_desc = board->code;
+
+	board->entry = (void*)((char*)board->code + high_desc->entry_rel);
+
+	board->ds = get_data_segment();
+
+	ret = cgeb_call_simple(board, CgebGetCgebVersion, 0, NULL, &dw);
+	if (ret)
+		goto err_vfree;
+
+	if (CGEB_GET_VERSION_MAJOR(dw) != CGEB_VERSION_MAJOR)
+		goto err_vfree;
+
+	pr_debug("CGEB: BIOS interface revision: %d.%d\n",
+			dw >> 16, dw & 0xffff);
+
+	if (high_desc->data_size) {
+		board->data = vmalloc(high_desc->data_size);
+		if (!board->data)
+			goto err_vfree;
+	} else {
+		 ret = cgeb_call_simple(board, CgebGetDataSize, 0, NULL, &dw);
+		 if (!ret && dw) {
+			board->data = vmalloc(dw);
+			if (!board->data)
+				goto err_vfree;
+		}
+	}
+
+	ret = cgeb_call_simple(board, CgebOpen, 0, NULL, NULL);
+	if (ret)
+		goto err_vfree_data;
+
+	ret = cgeb_map_memory(board);
+	if (ret)
+		goto err_free_map;
+
+	ret = cgeb_call_simple(board, CgebBoardGetInfo, 0, (void*)&pbi, NULL);
+	if (ret)
+		goto err_free_map;
+
+	pr_info("CGEB: Board name: %c%c%c%c\n",
+			pbi->board[0], pbi->board[1],
+			pbi->board[2], pbi->board[3]);
+
+	iounmap(high_desc_virt);
+
+	return board;
+
+err_free_map:
+	cgeb_unmap_memory(board);
+err_vfree_data:
+	vfree(board->data);
+err_vfree:
+	vfree(board->code);
+err_iounmap:
+	iounmap(high_desc_virt);
+err_kfree:
+	kfree(board);
+	return NULL;
+}
+
+static void cgeb_close(struct cgeb_board_data *board)
+{
+	cgeb_call_simple(board, CgebClose, 0, NULL, NULL);
+
+	cgeb_unmap_memory(board);
+
+	vfree(board->data);
+	vfree(board->code);
+}
+
+static unsigned long cgeb_i2c_get_type(struct cgeb_board_data *brd, int unit)
+{
+	struct cgeb_i2c_info *info;
+	int ret;
+
+	ret = cgeb_call_simple(brd, CgebI2CGetInfo, unit, (void *) &info, NULL);
+	if (ret)
+		return ret;
+	if (!info)
+		return -EINVAL;
+	return info->type;
+}
+
+static struct cgeb_board_data *cgeb_board;
+
+static int __init cgeb_init(void)
+{
+	struct cgeb_board_data *board;
+	resource_size_t base;
+	int i, ret;
+	struct cgeb_pdata pdata;
+	u32 i2c_count, watchdog_count;
+	int num_devices = 0;
+
+	for (base = 0xf0000; base >= 0xc0000; base -= 0x10000) {
+		board = cgeb_open(base, 0x10000);
+		if (board)
+			break;
+	}
+
+	if (!board)
+		return -ENODEV;
+
+	cgeb_board = board;
+
+	pdata.board = board;
+
+	cgeb_call_simple(board, CgebI2CCount, 0, NULL, &i2c_count);
+	cgeb_call_simple(board, CgebWDogCount, 0, NULL, &watchdog_count);
+
+	board->num_devices = i2c_count + watchdog_count;
+	board->devices = kzalloc(sizeof(void *) * (board->num_devices),
+			 GFP_KERNEL);
+	if (!board->devices) {
+		ret = -ENOMEM;
+		goto err_out;
+	}
+
+	for (i = 0; i < i2c_count; i++) {
+		ret = cgeb_i2c_get_type(board, i);
+		if (ret != CGEB_I2C_TYPE_PRIMARY)
+			continue;
+
+		 pdata.unit = i;
+
+		 board->devices[num_devices] =
+			platform_device_register_data(NULL, "cgeb-i2c", i,
+					&pdata, sizeof(pdata));
+		 num_devices++;
+	}
+
+	for (i = 0; i < watchdog_count; i++) {
+		board->devices[num_devices] =
+			platform_device_register_data(NULL, "cgeb-watchdog", i,
+					&pdata, sizeof(pdata));
+		pdata.unit = i;
+
+		num_devices++;
+	}
+
+	return 0;
+err_out:
+	cgeb_close(board);
+	kfree(board);
+
+	return ret;
+}
+
+static void __exit cgeb_exit(void)
+{
+	struct cgeb_board_data *board = cgeb_board;
+	int i;
+
+	for (i = 0; i < board->num_devices; i++)
+		if (board->devices[i])
+			platform_device_unregister(board->devices[i]);
+
+	cgeb_close(board);
+
+	kfree(board->devices);
+	kfree(board);
+}
+
+module_init(cgeb_init);
+module_exit(cgeb_exit);
+
+MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");
+MODULE_DESCRIPTION("CGEB driver");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/mfd/congatec-cgeb.h b/include/linux/mfd/congatec-cgeb.h
new file mode 100644
index 000000000000..26f5452286af
--- /dev/null
+++ b/include/linux/mfd/congatec-cgeb.h
@@ -0,0 +1,105 @@ 
+#ifndef __CONGATEC_CGEB_H
+#define __CONGATEC_CGEB_H
+
+/* CGEB interface functions */
+typedef enum {
+	CgebGetCgebVersion =            0,
+	CgebGetSysBiosVersion =         1,
+	CgebGetVgaBiosVersion =         2,
+	CgebGetDataSize =               3,
+	CgebOpen =                      4,
+	CgebClose =                     5,
+	CgebMapGetMem =                 6,
+	CgebMapChanged =                7,
+	CgebMapGetPorts =               8,
+	CgebDelayUs =                   9,
+	CgebCgbcReadWrite =             10,
+	CgebCgbcSetControl =            11,
+	CgebCgbcGetInfo =               12,
+	CgebCgbcHandleCommand =         13,
+	CgebBoardGetInfo =              14,
+	CgebBoardGetBootCounter =       15,
+	CgebBoardGetRunningTimeMeter =  16,
+	CgebBoardGetBootErrorLog =      17,
+	CgebVgaCount =                  18,
+	CgebVgaGetInfo =                19,
+	CgebVgaGetContrast =            20,
+	CgebVgaSetContrast =            21,
+	CgebVgaGetContrastEnable =      22,
+	CgebVgaSetContrastEnable =      23,
+	CgebVgaGetBacklight =           24,
+	CgebVgaSetBacklight =           25,
+	CgebVgaGetBacklightEnable =     26,
+	CgebVgaSetBacklightEnable =     27,
+	CgebVgaEndDarkBoot =            28,
+	CgebStorageAreaCount =          29,
+	CgebStorageAreaGetInfo =        30,
+	CgebStorageAreaRead =           31,
+	CgebStorageAreaWrite =          32,
+	CgebStorageAreaErase =          33,
+	CgebStorageAreaEraseStatus =    34,
+	CgebI2CCount =                  35,
+	CgebI2CGetInfo =                36,
+	CgebI2CGetAddrList =            37,
+	CgebI2CTransfer =               38,
+	CgebI2CGetFrequency =           39,
+	CgebI2CSetFrequency =           40,
+	CgebIOCount =                   41,
+	CgebIOGetInfo =                 42,
+	CgebIORead =                    43,
+	CgebIOWrite =                   44,
+	CgebIOGetDirection =            45,
+	CgebIOSetDirection =            46,
+	CgebWDogCount =                 47,
+	CgebWDogGetInfo =               48,
+	CgebWDogTrigger =               49,
+	CgebWDogGetConfig =             50,
+	CgebWDogSetConfig =             51,
+	CgebPerformanceGetCurrent =     52,
+	CgebPerformanceSetCurrent =     53,
+	CgebPerformanceGetPolicyCaps =  54,
+	CgebPerformanceGetPolicy =      55,
+	CgebPerformanceSetPolicy =      56,
+	CgebTemperatureCount =          57,
+	CgebTemperatureGetInfo =        58,
+	CgebTemperatureGetCurrent =     59,
+	CgebTemperatureSetLimits =      60,
+	CgebFanCount =                  61,
+	CgebFanGetInfo =                62,
+	CgebFanGetCurrent =             63,
+	CgebFanSetLimits =              64,
+	CgebVoltageCount =              65,
+	CgebVoltageGetInfo =            66,
+	CgebVoltageGetCurrent =         67,
+	CgebVoltageSetLimits =          68,
+	CgebStorageAreaLock =           69,
+	CgebStorageAreaUnlock =         70,
+	CgebStorageAreaIsLocked =       71,
+} cgeb_function_t;
+
+struct cgeb_function_parameters {
+	u32 unit;               /* unit number or type */
+	u32 pars[4];            /* input parameters */
+	u32 rets[2];            /* return parameters */
+	void *iptr;             /* input pointer */
+	void *optr;             /* output pointer */
+};
+
+struct cgeb_board_data;
+
+unsigned int cgeb_call(struct cgeb_board_data *,
+		struct cgeb_function_parameters *, cgeb_function_t);
+
+int cgeb_call_simple(struct cgeb_board_data *,
+		cgeb_function_t, u32,
+		void **, u32 *);
+
+/*
+ * Platform data for child devices
+ */
+struct cgeb_pdata {
+	struct cgeb_board_data *board;
+	int unit;
+};
+
+#endif /* __CONGATEC_CGEB_H */