Commit dcc7d344 authored by Vignesh Raghavendra's avatar Vignesh Raghavendra Committed by Miquel Raynal

mtd: Add support for HyperBus memory devices

Cypress' HyperBus is Low Signal Count, High Performance Double Data Rate
Bus interface between a host system master and one or more slave
interfaces. HyperBus is used to connect microprocessor, microcontroller,
or ASIC devices with random access NOR flash memory (called HyperFlash)
or self refresh DRAM (called HyperRAM).

Its a 8-bit data bus (DQ[7:0]) with  Read-Write Data Strobe (RWDS)
signal and either Single-ended clock(3.0V parts) or Differential clock
(1.8V parts). It uses ChipSelect lines to select b/w multiple slaves.
At bus level, it follows a separate protocol described in HyperBus

HyperFlash follows CFI AMD/Fujitsu Extended Command Set (0x0002) similar
to that of existing parallel NORs. Since HyperBus is x8 DDR bus,
its equivalent to x16 parallel NOR flash with respect to bits per clock
cycle. But HyperBus operates at >166MHz frequencies.
HyperRAM provides direct random read/write access to flash memory

But, HyperBus memory controllers seem to abstract implementation details
and expose a simple MMIO interface to access connected flash.

Add support for registering HyperFlash devices with MTD framework. MTD
maps framework along with CFI chip support framework are used to support
communicating with flash.

Framework is modelled along the lines of spi-nor framework. HyperBus
memory controller (HBMC) drivers calls hyperbus_register_device() to
register a single HyperFlash device. HyperFlash core parses MMIO access
information from DT, sets up the map_info struct, probes CFI flash and
registers it with MTD framework.

Some HBMC masters need calibration/training sequence[3] to be carried
out, in order for DLL inside the controller to lock, by reading a known
string/pattern. This is done by repeatedly reading CFI Query
Identification String. Calibration needs to be done before trying to detect
flash as part of CFI flash probe.

HyperRAM is not supported at the moment.

HyperBus specification can be found at[1]
HyperFlash datasheet can be found at[2]

    Table 12-5741. HyperFlash Access Sequence
Signed-off-by: default avatarVignesh Raghavendra <>
Signed-off-by: default avatarMiquel Raynal <>
parent 89ebf2b8
......@@ -7305,6 +7305,13 @@ F: include/uapi/linux/hyperv.h
F: tools/hv/
F: Documentation/ABI/stable/sysfs-bus-vmbus
M: Vignesh Raghavendra <>
S: Supported
F: drivers/mtd/hyperbus/
F: include/linux/mtd/hyperbus.h
F: Documentation/devicetree/bindings/mtd/cypress,hyperflash.txt
S: Odd Fixes
......@@ -274,4 +274,6 @@ source "drivers/mtd/spi-nor/Kconfig"
source "drivers/mtd/ubi/Kconfig"
source "drivers/mtd/hyperbus/Kconfig"
endif # MTD
......@@ -34,3 +34,4 @@ obj-y += chips/ lpddr/ maps/ devices/ nand/ tests/
obj-$(CONFIG_MTD_SPI_NOR) += spi-nor/
obj-$(CONFIG_MTD_UBI) += ubi/
obj-$(CONFIG_MTD_HYPERBUS) += hyperbus/
menuconfig MTD_HYPERBUS
tristate "HyperBus support"
select MTD_CFI
This is the framework for the HyperBus which can be used by
the HyperBus Controller driver to communicate with
HyperFlash. See Cypress HyperBus specification for more
# SPDX-License-Identifier: GPL-2.0
obj-$(CONFIG_MTD_HYPERBUS) += hyperbus-core.o
// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2019 Texas Instruments Incorporated -
// Author: Vignesh Raghavendra <>
#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mtd/hyperbus.h>
#include <linux/mtd/map.h>
#include <linux/mtd/mtd.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/types.h>
static struct hyperbus_device *map_to_hbdev(struct map_info *map)
return container_of(map, struct hyperbus_device, map);
static map_word hyperbus_read16(struct map_info *map, unsigned long addr)
struct hyperbus_device *hbdev = map_to_hbdev(map);
struct hyperbus_ctlr *ctlr = hbdev->ctlr;
map_word read_data;
read_data.x[0] = ctlr->ops->read16(hbdev, addr);
return read_data;
static void hyperbus_write16(struct map_info *map, map_word d,
unsigned long addr)
struct hyperbus_device *hbdev = map_to_hbdev(map);
struct hyperbus_ctlr *ctlr = hbdev->ctlr;
ctlr->ops->write16(hbdev, addr, d.x[0]);
static void hyperbus_copy_from(struct map_info *map, void *to,
unsigned long from, ssize_t len)
struct hyperbus_device *hbdev = map_to_hbdev(map);
struct hyperbus_ctlr *ctlr = hbdev->ctlr;
ctlr->ops->copy_from(hbdev, to, from, len);
static void hyperbus_copy_to(struct map_info *map, unsigned long to,
const void *from, ssize_t len)
struct hyperbus_device *hbdev = map_to_hbdev(map);
struct hyperbus_ctlr *ctlr = hbdev->ctlr;
ctlr->ops->copy_to(hbdev, to, from, len);
int hyperbus_register_device(struct hyperbus_device *hbdev)
const struct hyperbus_ops *ops;
struct hyperbus_ctlr *ctlr;
struct device_node *np;
struct map_info *map;
struct resource res;
struct device *dev;
int ret;
if (!hbdev || !hbdev->np || !hbdev->ctlr || !hbdev->ctlr->dev) {
pr_err("hyperbus: please fill all the necessary fields!\n");
return -EINVAL;
np = hbdev->np;
ctlr = hbdev->ctlr;
if (!of_device_is_compatible(np, "cypress,hyperflash"))
return -ENODEV;
hbdev->memtype = HYPERFLASH;
ret = of_address_to_resource(np, 0, &res);
if (ret)
return ret;
dev = ctlr->dev;
map = &hbdev->map;
map->size = resource_size(&res);
map->virt = devm_ioremap_resource(dev, &res);
if (IS_ERR(map->virt))
return PTR_ERR(map->virt);
map->name = dev_name(dev);
map->bankwidth = 2;
map->device_node = np;
ops = ctlr->ops;
if (ops) {
if (ops->read16)
map->read = hyperbus_read16;
if (ops->write16)
map->write = hyperbus_write16;
if (ops->copy_to)
map->copy_to = hyperbus_copy_to;
if (ops->copy_from)
map->copy_from = hyperbus_copy_from;
if (ops->calibrate && !ctlr->calibrated) {
ret = ops->calibrate(hbdev);
if (!ret) {
dev_err(dev, "Calibration failed\n");
return -ENODEV;
ctlr->calibrated = true;
hbdev->mtd = do_map_probe("cfi_probe", map);
if (!hbdev->mtd) {
dev_err(dev, "probing of hyperbus device failed\n");
return -ENODEV;
hbdev->mtd->dev.parent = dev;
mtd_set_of_node(hbdev->mtd, np);
ret = mtd_device_register(hbdev->mtd, NULL, 0);
if (ret) {
dev_err(dev, "failed to register mtd device\n");
return ret;
return 0;
int hyperbus_unregister_device(struct hyperbus_device *hbdev)
int ret = 0;
if (hbdev && hbdev->mtd) {
ret = mtd_device_unregister(hbdev->mtd);
return ret;
MODULE_DESCRIPTION("HyperBus Framework");
MODULE_AUTHOR("Vignesh Raghavendra <>");
/* SPDX-License-Identifier: GPL-2.0
* Copyright (C) 2019 Texas Instruments Incorporated -
#include <linux/mtd/map.h>
enum hyperbus_memtype {
* struct hyperbus_device - struct representing HyperBus slave device
* @map: map_info struct for accessing MMIO HyperBus flash memory
* @np: pointer to HyperBus slave device node
* @mtd: pointer to MTD struct
* @ctlr: pointer to HyperBus controller struct
* @memtype: type of memory device: HyperFlash or HyperRAM
struct hyperbus_device {
struct map_info map;
struct device_node *np;
struct mtd_info *mtd;
struct hyperbus_ctlr *ctlr;
enum hyperbus_memtype memtype;
* struct hyperbus_ops - struct representing custom HyperBus operations
* @read16: read 16 bit of data from flash in a single burst. Used to read
* from non default address space, such as ID/CFI space
* @write16: write 16 bit of data to flash in a single burst. Used to
* send cmd to flash or write single 16 bit word at a time.
* @copy_from: copy data from flash memory
* @copy_to: copy data to flash memory
* @calibrate: calibrate HyperBus controller
struct hyperbus_ops {
u16 (*read16)(struct hyperbus_device *hbdev, unsigned long addr);
void (*write16)(struct hyperbus_device *hbdev,
unsigned long addr, u16 val);
void (*copy_from)(struct hyperbus_device *hbdev, void *to,
unsigned long from, ssize_t len);
void (*copy_to)(struct hyperbus_device *dev, unsigned long to,
const void *from, ssize_t len);
int (*calibrate)(struct hyperbus_device *dev);
* struct hyperbus_ctlr - struct representing HyperBus controller
* @dev: pointer to HyperBus controller device
* @calibrated: flag to indicate ctlr calibration sequence is complete
* @ops: HyperBus controller ops
struct hyperbus_ctlr {
struct device *dev;
bool calibrated;
const struct hyperbus_ops *ops;
* hyperbus_register_device - probe and register a HyperBus slave memory device
* @hbdev: hyperbus_device struct with dev, np and ctlr field populated
* Return: 0 for success, others for failure.
int hyperbus_register_device(struct hyperbus_device *hbdev);
* hyperbus_unregister_device - deregister HyperBus slave memory device
* @hbdev: hyperbus_device to be unregistered
* Return: 0 for success, others for failure.
int hyperbus_unregister_device(struct hyperbus_device *hbdev);
#endif /* __LINUX_MTD_HYPERBUS_H__ */
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