This was fixed by David Lamparter in v2.6.36-rc5 3486008 ("spi: free
children in spi_unregister_master, not siblings") and broken again in
v2.6.37-rc1~2^2~4 during the merge of 2b9603a0 ("spi: enable
spi_board_info to be registered after spi_master").
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: David Lamparter <equinox@diac24.net>
Cc: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is a possibility that the last word of a transaction will be lost
if data is not ready. Re-read in poll_transfer() to solve this issue
when poll_mode is enabled.
Verified on SPI touch screen device.
Signed-off-by: Major Lee <major_lee@wistron.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
passing argument 2 of 'dma_map_single' discards qualifiers from pointer target type
Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
* 'next-spi' of git://git.secretlab.ca/git/linux-2.6:
spi/pl022: fix erroneous platform data in U300
spi: fixed odd static string conventions in core code
spi/bfin_spi: only request GPIO on first load
spi/bfin_spi: handle error/status changes after data interrupts
spi: enable spi_board_info to be registered after spi_master
* 'llseek' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl:
vfs: make no_llseek the default
vfs: don't use BKL in default_llseek
llseek: automatically add .llseek fop
libfs: use generic_file_llseek for simple_attr
mac80211: disallow seeks in minstrel debug code
lirc: make chardev nonseekable
viotape: use noop_llseek
raw: use explicit llseek file operations
ibmasmfs: use generic_file_llseek
spufs: use llseek in all file operations
arm/omap: use generic_file_llseek in iommu_debug
lkdtm: use generic_file_llseek in debugfs
net/wireless: use generic_file_llseek in debugfs
drm: use noop_llseek
This patch removes convention of passing a static string as a
parameter to another static string. The convention is intended to
reduce text usage by sharing the common bits of the string, but the
implementation is inherently fragile (a change to one format string
but not the other will nullify any possible advantage), it isn't
necessarily a net win depending on what this compiler does, and it
it reduces code readability.
Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
[grant.likely@secretlab.ca: removed dev_dbg->dev_err hunk]
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
The gpiolib code does not allow people to do gpio_request() on a GPIO
once it has already been requested. So make sure we only request the
pin on the first setup of a SPI device. Otherwise, if you attempts to
reconfigure a SPI device on the fly (like change bit sizes), the setup
function incorrectly fails.
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
The error interrupt on the BF537 SIC cannot be enabled on a
per-peripheral basis. Once the error interrupt is enabled
for one peripheral, it is automatically enabled for all.
So in the Blackfin on-chip SPI driver, we need to clear out
these known errors in the data interrupt once we've successfully
finished processing all of the pending data.
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Currently spi_register_board_info() has to be called before its related
spi_master be registered, otherwise these board info will be just ignored.
This patch will remove this order limit, it adds a global spi master list
like the existing global board info listr. Whenever a board info or a
spi_master is registered, the spi master list or board info list
will be scanned, and a new spi device will be created if there is a
master-board info match.
Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
v2 changes:
from Thierry Reding:
* add "select TEGRA_SYSTEM_DMA" to Kconfig
from Grant Likely:
* add oneline description to header
* inline references to DRIVER_NAME
* inline references to BUSY_TIMEOUT
* open coded bytes_per_word()
* spi_readl/writel -> spi_tegra_readl/writel
* move transfer validation to spi_tegra_transfer
* don't request_mem_region iomem as platform bus does that for us
* __exit -> __devexit
v3 changes:
from Russell King:
* put request_mem_region back int
from Grant Likely:
* remove #undef DEBUG
* add SLINK_ to register bit defines
* remove unused bytes_per_word
* make spi_tegra_readl/writel static linine
* various refactoring for clarity
* mark err if BSY bit is not cleared after 1000 retries
* move spinlock to protect setting of RDY bit
* subsys_initcall -> module_init
v3 changes:
from Grant Likely:
* update spi_tegra to use PTR_ERRless dma API
v4 changes:
from Grant Likely:
* remove empty spi_tegra_cleanup fucntion
* allow device ids of -1
Signed-off-by: Erik Gilling <konkers@android.com>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Cc: Thierry Reding <thierry.reding@avionic-design.de>
Cc: Russell King <linux@arm.linux.org.uk>
spi: tegra: cleanups from upstream review
Change-Id: Icecf7e64efcb39de072a15234ba1faa4bad40d25
Signed-off-by: Erik Gilling <konkers@android.com>
* 'devel' of master.kernel.org:/home/rmk/linux-2.6-arm: (278 commits)
arm: remove machine_desc.io_pg_offst and .phys_io
arm: use addruart macro to establish debug mappings
arm: return both physical and virtual addresses from addruart
arm/debug: consolidate addruart macros for CONFIG_DEBUG_ICEDCC
ARM: make struct machine_desc definition coherent with its comment
eukrea_mbimxsd-baseboard: Pass the correct GPIO to gpio_free
cpuimx27: fix compile when ULPI is selected
mach-pcm037_eet: fix compile errors
Fixing ethernet driver compilation error for i.MX31 ADS board
cpuimx51: update board support
mx5: add cpuimx51sd module and its baseboard
iomux-mx51: fix GPIO_1_xx 's IOMUX configuration
imx-esdhc: update devices registration
mx51: add resources for SD/MMC on i.MX51
iomux-mx51: fix SD1 and SD2's iomux configuration
clock-mx51: rename CLOCK1 to CLOCK_CCGR for better readability
clock-mx51: factorize clk_set_parent and clk_get_rate
eukrea_mbimxsd: add support for DVI displays
cpuimx25 & cpuimx35: fix OTG port registration in host mode
i.MX31 and i.MX35 : fix errate TLSbo65953 and ENGcm09472
...
In case of TX only with DMA, the driver assumes that the data
has been transferred once DMA callback in invoked. However,
SPI's shift register may still contain data. Thus, the driver
is supposed to verify that the register is empty and the end of
the SPI transfer has been reached.
Signed-off-by: Ilkka Koskinen <ilkka.koskinen@nokia.com>
Tested-by: Tuomas Katila <ext-tuomas.2.katila@nokia.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
In the TX_ONLY transfer, the SPI controller also receives data
simultaneously and saves them in the rx register. After the TX_ONLY
transfer, the rx register will hold the random data received during
the last tx transaction.
If the direct following transfer is RX_ONLY, this random data has the
possibility to affect this transfer like this:
When the SPI controller is changed from TX_ONLY to RX_ONLY,
the random data makes the rx register full immediately and
triggers a dummy write automatically(in SPI RX_ONLY transfers,
we need a dummy write to trigger the first transaction).
So the first data received in the RX_ONLY transfer will be that
random data instead of something meaningful.
We can avoid this by inserting a Disable/Re-enable toggle of the
channel after the TX_ONLY transfer, since it purges the rx register.
Signed-off-by: Jason Wang <jason77.wang@gmail.com>
Tested-by: Grazvydas Ignotas <notasas@gmail.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Some systems using this bus sometimes have very basic devices on them
such as regulators. So we need to be loaded even earlier in case the
devices are used by things such as early board init code. Therefore
register in subsys_initcall().
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Currently, if the bits_per_word when doing a transfer is not 8bits, we
always treat it as 16bits when we should actually be returning an error.
Signed-off-by: Bob Liu <lliubbo@gmail.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
When the hardware is controlling the CS, there are some SPI options
we are unable to support. So issue a warning in the hopes that the
user will change to a SPI mode where we can support things sanely.
Signed-off-by: Barry Song <barry.song@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Using disable_irq() on the IRQ whose handler we are currently executing in
can easily lead to a hang. So use the nosync variant here.
Signed-off-by: Barry Song <barry.song@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
While combining things, also switch to the proper SPI bit define names.
This lets us punt the rarely used SPI defines.
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
During runtime, the spi setup function may be called multiple times on the
same device in order to reconfigure some settings on the fly. When this
happens, we need to reset the ctl_reg bits so that changing the mode works
as expected.
Reported-by: Andy Getzendanner <james.getzendanner@students.olin.edu>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
This reduces duplication between the setup/transfer functions and keeps
values cached during setup from overriding values changed on a transfer
basis (like bits_per_word).
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Using disable_irq() on the IRQ whose handler we are currently executing in
can easily lead to a hang. So use the nosync variant here.
Signed-off-by: Yi Li <yi.li@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Sometimes under load, the Blackfin core is able to send SPI register
updates out before the controller is actually disabled. So when we
go to reprogram the entire state (to switch to a different slave),
make sure we sync after disabling the controller.
Signed-off-by: Barry Song <barry.song@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
We can't rely on the SPI_CTL/SPI_FLG registers retaining their state when
suspending, so save/restore their entire values.
Signed-off-by: Barry Song <barry.song@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
The common SPI layers take care of detecting CS conflicts and preventing
two devices from claiming the same CS. This causes problems for the GPIO
CS support we currently have as we are using CS0 to mean "GPIO CS". But
if we have multiple devices using a GPIO CS, the common SPI layers see
multiple devices using the virtual "CS0" and reject any such attempts.
To make both work, we introduce an offset define. This represents the
max number of hardware CS values that the SPI peripheral supports. If
the CS is below this limit, we know we can use the hardware CS. If it's
above, we treat it as a GPIO CS. This keeps the CS unique as seen by
the common code and prevents conflicts.
Signed-off-by: Barry Song <barry.song@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
The driver that we based ours on uses a little extra memory behind the
normal driver state, but we don't. So drop this useless bit of memory.
Reported-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
The current structure names are a bit confusing as to what they represent,
so use better names.
Reported-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Rather than having to look up the same 3 sets of functions at the same
time, just use an ops structure so we only need to set one pointer.
Reported-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
No point in creating our own version of true/false defines when there is
already a standard stdbool available to us.
Reported-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
The chip ops should always be initialized, so having null fallback
functions are useless.
Reported-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
As David points out, the cs_change_per_word option isn't standard, nor is
anyone actually using it. So punt all of the dead code considering it
makes up ~10% of the code size.
Reported-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
The CS helper functions were toggling both the Flag Enable and the Flag
Value bits, but the Flag Value bit is ignored if the corresponding Flag
Enable bit is cleared. So under high speed transactions, the CS sometimes
would not toggle properly.
Since it makes no sense to toggle the Flag Enable bit dynamically when we
actually want to control the Flag Value, do this when setting up the device
and then only handle toggling of the CS value during runtime.
Signed-off-by: Barry Song <barry.song@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
The current behavior in PIO mode is to poll the SPI status registers which
can obviously lead to higher latencies when doing a lot of SPI traffic.
There is a SPI interrupt which can be used instead to signal individual
completion of transactions.
Signed-off-by: Yi Li <yi.li@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
We should make sure the SPI controller is in a sane state in case the
boot loader left it in a crappy state. Such as DMA pending which causes
interrupts to fire on us.
When setting a sane initial state, do not default to slave mode. If we
do, then the SPI peripheral may implicitly take over the SPISS pin which
other things might be using.
For example, the BF533-STAMP uses this pin as a GPIO to control switching
between ethernet and flash. If the SPI peripheral controls the output
state instead, the ethernet is no longer accessible.
URL: http://blackfin.uclinux.org/gf/tracker/5630
Signed-off-by: Wolfgang Muees <wolfgang.mues@auerswald.de>
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Anomaly 05000119 states that the DMA_RUN bit with peripherals isn't
reliable. However, the way the driver is currently written (DMA IRQ
callback), we don't need the polling in the first place, so drop it.
Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Re-order setup() a bit so we don't leak memory/dma/gpio resources upon
errors. Also make sure we don't call kfree() twice on the same object.
Signed-off-by: Daniel Mack <daniel@caiaq.de>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Signed-off-by: Yi Li <yi.li@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
This patches a typo in the debug message.
Signed-off-by: Matthias Brugger <mensch0815@gmail.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
All file_operations should get a .llseek operation so we can make
nonseekable_open the default for future file operations without a
.llseek pointer.
The three cases that we can automatically detect are no_llseek, seq_lseek
and default_llseek. For cases where we can we can automatically prove that
the file offset is always ignored, we use noop_llseek, which maintains
the current behavior of not returning an error from a seek.
New drivers should normally not use noop_llseek but instead use no_llseek
and call nonseekable_open at open time. Existing drivers can be converted
to do the same when the maintainer knows for certain that no user code
relies on calling seek on the device file.
The generated code is often incorrectly indented and right now contains
comments that clarify for each added line why a specific variant was
chosen. In the version that gets submitted upstream, the comments will
be gone and I will manually fix the indentation, because there does not
seem to be a way to do that using coccinelle.
Some amount of new code is currently sitting in linux-next that should get
the same modifications, which I will do at the end of the merge window.
Many thanks to Julia Lawall for helping me learn to write a semantic
patch that does all this.
===== begin semantic patch =====
// This adds an llseek= method to all file operations,
// as a preparation for making no_llseek the default.
//
// The rules are
// - use no_llseek explicitly if we do nonseekable_open
// - use seq_lseek for sequential files
// - use default_llseek if we know we access f_pos
// - use noop_llseek if we know we don't access f_pos,
// but we still want to allow users to call lseek
//
@ open1 exists @
identifier nested_open;
@@
nested_open(...)
{
<+...
nonseekable_open(...)
...+>
}
@ open exists@
identifier open_f;
identifier i, f;
identifier open1.nested_open;
@@
int open_f(struct inode *i, struct file *f)
{
<+...
(
nonseekable_open(...)
|
nested_open(...)
)
...+>
}
@ read disable optional_qualifier exists @
identifier read_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
expression E;
identifier func;
@@
ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off)
{
<+...
(
*off = E
|
*off += E
|
func(..., off, ...)
|
E = *off
)
...+>
}
@ read_no_fpos disable optional_qualifier exists @
identifier read_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
@@
ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off)
{
... when != off
}
@ write @
identifier write_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
expression E;
identifier func;
@@
ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off)
{
<+...
(
*off = E
|
*off += E
|
func(..., off, ...)
|
E = *off
)
...+>
}
@ write_no_fpos @
identifier write_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
@@
ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off)
{
... when != off
}
@ fops0 @
identifier fops;
@@
struct file_operations fops = {
...
};
@ has_llseek depends on fops0 @
identifier fops0.fops;
identifier llseek_f;
@@
struct file_operations fops = {
...
.llseek = llseek_f,
...
};
@ has_read depends on fops0 @
identifier fops0.fops;
identifier read_f;
@@
struct file_operations fops = {
...
.read = read_f,
...
};
@ has_write depends on fops0 @
identifier fops0.fops;
identifier write_f;
@@
struct file_operations fops = {
...
.write = write_f,
...
};
@ has_open depends on fops0 @
identifier fops0.fops;
identifier open_f;
@@
struct file_operations fops = {
...
.open = open_f,
...
};
// use no_llseek if we call nonseekable_open
////////////////////////////////////////////
@ nonseekable1 depends on !has_llseek && has_open @
identifier fops0.fops;
identifier nso ~= "nonseekable_open";
@@
struct file_operations fops = {
... .open = nso, ...
+.llseek = no_llseek, /* nonseekable */
};
@ nonseekable2 depends on !has_llseek @
identifier fops0.fops;
identifier open.open_f;
@@
struct file_operations fops = {
... .open = open_f, ...
+.llseek = no_llseek, /* open uses nonseekable */
};
// use seq_lseek for sequential files
/////////////////////////////////////
@ seq depends on !has_llseek @
identifier fops0.fops;
identifier sr ~= "seq_read";
@@
struct file_operations fops = {
... .read = sr, ...
+.llseek = seq_lseek, /* we have seq_read */
};
// use default_llseek if there is a readdir
///////////////////////////////////////////
@ fops1 depends on !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier readdir_e;
@@
// any other fop is used that changes pos
struct file_operations fops = {
... .readdir = readdir_e, ...
+.llseek = default_llseek, /* readdir is present */
};
// use default_llseek if at least one of read/write touches f_pos
/////////////////////////////////////////////////////////////////
@ fops2 depends on !fops1 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier read.read_f;
@@
// read fops use offset
struct file_operations fops = {
... .read = read_f, ...
+.llseek = default_llseek, /* read accesses f_pos */
};
@ fops3 depends on !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier write.write_f;
@@
// write fops use offset
struct file_operations fops = {
... .write = write_f, ...
+ .llseek = default_llseek, /* write accesses f_pos */
};
// Use noop_llseek if neither read nor write accesses f_pos
///////////////////////////////////////////////////////////
@ fops4 depends on !fops1 && !fops2 && !fops3 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier read_no_fpos.read_f;
identifier write_no_fpos.write_f;
@@
// write fops use offset
struct file_operations fops = {
...
.write = write_f,
.read = read_f,
...
+.llseek = noop_llseek, /* read and write both use no f_pos */
};
@ depends on has_write && !has_read && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier write_no_fpos.write_f;
@@
struct file_operations fops = {
... .write = write_f, ...
+.llseek = noop_llseek, /* write uses no f_pos */
};
@ depends on has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier read_no_fpos.read_f;
@@
struct file_operations fops = {
... .read = read_f, ...
+.llseek = noop_llseek, /* read uses no f_pos */
};
@ depends on !has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
@@
struct file_operations fops = {
...
+.llseek = noop_llseek, /* no read or write fn */
};
===== End semantic patch =====
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Julia Lawall <julia@diku.dk>
Cc: Christoph Hellwig <hch@infradead.org>
We get the following when building on ppc64 due to lack of include of
<asm/io.h>:
In file included from drivers/spi/spi_fsl_espi.c:25:0:
drivers/spi/spi_fsl_lib.h: In function 'mpc8xxx_spi_write_reg':
drivers/spi/spi_fsl_lib.h:88:2: error: implicit declaration of function 'out_be32'
drivers/spi/spi_fsl_lib.h: In function 'mpc8xxx_spi_read_reg':
drivers/spi/spi_fsl_lib.h:93:2: error: implicit declaration of function 'in_be32'
drivers/spi/spi_fsl_espi.c: In function 'fsl_espi_remove':
drivers/spi/spi_fsl_espi.c:571:2: error: implicit declaration of function 'iounmap'
drivers/spi/spi_fsl_espi.c: In function 'fsl_espi_probe':
drivers/spi/spi_fsl_espi.c:602:2: error: implicit declaration of function 'ioremap'
drivers/spi/spi_fsl_espi.c:602:24: warning: assignment makes pointer from integer without a cast
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
bits_per_word option in spi_transfer are allowed if it does not change
the csr register.
This is necessary for the driver in
drivers/staging/iio/adis16260_core.c, as it uses this option.
Signed-off-by: Matthias Brugger <mensch0815@gmail.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
This patch fixes the following build error introduced by commit
65308c46, "spi/topcliff: cleanup for style and conciseness".
drivers/spi/spi_topcliff_pch.c: In function 'pch_spi_process_messages':
drivers/spi/spi_topcliff_pch.c:752: warning: 'data' is used uninitialized in
+this function
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Add eSPI controller support based on the library code spi_fsl_lib.c.
The eSPI controller is newer controller 85xx/Pxxx devices supported.
There're some differences comparing to the SPI controller:
1. Has different register map and different bit definition
So leave the code operated the register to the driver code, not
the common code.
2. Support 4 dedicated chip selects
The software can't controll the chip selects directly, The SPCOM[CS]
field is used to select which chip selects is used, and the
SPCOM[TRANLEN] field is set to tell the controller how long the CS
signal need to be asserted. So the driver doesn't need the chipselect
related function when transfering data, just set corresponding register
fields to controll the chipseclect.
3. Different Transmit/Receive FIFO access register behavior
For SPI controller, the Tx/Rx FIFO access register can hold only
one character regardless of the character length, but for eSPI
controller, the register can hold 4 or 2 characters according to
the character lengths. Access the Tx/Rx FIFO access register of the
eSPI controller will shift out/in 4/2 characters one time. For SPI
subsystem, the command and data are put into different transfers, so
we need to combine all the transfers to one transfer in order to pass
the transfer to eSPI controller.
4. The max transaction length limitation
The max transaction length one time is limitted by the SPCOM[TRANSLEN]
field which is 0xFFFF. When used mkfs.ext2 command to create ext2
filesystem on the flash, the read length will exceed the max value of
the SPCOM[TRANSLEN] field.
Signed-off-by: Mingkai Hu <Mingkai.hu@freescale.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
