aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/fsi/fsi-master-gpio.c (follow)
AgeCommit message (Collapse)AuthorFilesLines
2019-05-21treewide: Add SPDX license identifier for more missed filesThomas Gleixner1-0/+1
Add SPDX license identifiers to all files which: - Have no license information of any form - Have MODULE_LICENCE("GPL*") inside which was used in the initial scan/conversion to ignore the file These files fall under the project license, GPL v2 only. The resulting SPDX license identifier is: GPL-2.0-only Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-07-12fsi: Move various master definitions to a common headerBenjamin Herrenschmidt1-29/+0
This moves the definitions for various protocol details (message & response codes, delays etc...) out of fsi-master-gpio.c to fsi-master.h in order to share them with other master implementations. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Reviewed-by: Joel Stanley <joel@jms.id.au>
2018-07-12fsi: master-gpio: Add missing release functionBenjamin Herrenschmidt1-18/+35
The embedded struct device needs a release function to be able to successfully remove the driver. We remove the devm_gpiod_put() as they are unnecessary (the resources will be released automatically) and because fsi_master_unregister() will cause the master structure to be freed. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Reviewed-by: Joel Stanley <joel@jms.id.au>
2018-07-12fsi: master-gpio: Remove "GPIO" prefix on some definitionsBenjamin Herrenschmidt1-34/+36
Some definitions are generic to the FSI protocol or any give master implementation. Rename them to remove the "GPIO" prefix in preparation for moving them to a common header. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Reviewed-by: Joel Stanley <joel@jms.id.au> # Conflicts: # drivers/fsi/fsi-master-gpio.c
2018-07-12fsi: master-gpio: Remove unused definitionsBenjamin Herrenschmidt1-6/+0
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Reviewed-by: Joel Stanley <joel@jms.id.au>
2018-07-12fsi: master-gpio: Add more tracepointsBenjamin Herrenschmidt1-6/+10
This adds a few more tracepoints that have proven useful when debugging issues with the FSI bus. This also makes echo_delay() use clock_zeros() instead of open-code it in order to share the tracepoint. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Reviewed-by: Joel Stanley <joel@jms.id.au>
2018-07-12fsi: master-gpio: Add support for link_configBenjamin Herrenschmidt1-2/+25
To configure the send and echo delays Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Reviewed-by: Joel Stanley <joel@jms.id.au>
2018-07-12fsi: master-gpio: Rename and adjust send delayBenjamin Herrenschmidt1-3/+6
What the driver called "FSI_GPIO_PRIME_SLAVE_CLOCKS" is what the FSI spec calls tSendDelay and should be 16 clocks by default. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Reviewed-by: Joel Stanley <joel@jms.id.au>
2018-06-12fsi/master-gpio: Replace bit_bit lock with IRQ disable/enableJeremy Kerr1-25/+23
We currently use a spinlock (bit_lock) around operations that clock bits out of the FSI bus, and a mutex to protect against simultaneous access to the master. This means that bit_lock isn't needed for mutual exlusion, only to prevent timing issues when clocking bits out. To reflect this, this change converts bit_lock to just the local_irq_save/restore operation. Signed-off-by: Jeremy Kerr <jk@ozlabs.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Tested-by: Joel Stanley <joel@jms.id.au>
2018-06-12fsi/fsi-master-gpio: More error handling cleanupBenjamin Herrenschmidt1-21/+5
Remove calls to the empty and useless fsi_master_gpio_error() function, and report CRC errors as "FSI_ERR_NO_SLAVE" when reading an all 1's response. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Tested-by: Joel Stanley <joel@jms.id.au>
2018-06-12fsi/fsi-master-gpio: Implement CRC error recoveryBenjamin Herrenschmidt1-18/+72
The FSI protocol defines two modes of recovery from CRC errors, this implements both: - If the device returns an ECRC (it detected a CRC error in the command), then we simply issue the command again. - If the master detects a CRC error in the response, we send an E_POLL command which requests a resend of the response without actually re-executing the command (which could otherwise have unwanted side effects such as dequeuing a FIFO twice). Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Reviewed-by: Christopher Bostic <cbostic@linux.vnet.ibm.com> Tested-by: Joel Stanley <joel@jms.id.au> --- Note: This was actually tested by removing some of my fixes, thus causing us to hit occasional CRC errors during high LPC activity.
2018-06-12fsi/gpio: Use relative-addressing commandsJeremy Kerr1-11/+91
FSI CFAMs support shorter commands that use a relative (or same) address as the last. This change introduces a last_addr to the master state, and uses it for subsequent reads/writes, and performs relative addressing when a subsequent read/write is in range. Signed-off-by: Jeremy Kerr <jk@ozlabs.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Reviewed-by: Christopher Bostic <cbostic@linux.vnet.ibm.com> Tested-by: Joel Stanley <joel@jms.id.au>
2018-06-12fsi/gpio: Include command build in locked sectionJeremy Kerr1-7/+18
For implementing relative addressing mode, we'll need to build a command that is coherent with CFAM state. To do that, include the build_command_* functions in the locked section of read/write/term. Signed-off-by: Jeremy Kerr <jk@ozlabs.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Tested-by: Joel Stanley <joel@jms.id.au>
2018-06-12fsi/fsi-master-gpio: Delay sampling of FSI data inputBenjamin Herrenschmidt1-0/+5
Most SoC GPIO implementations, including the Aspeed one, have synchronizers on the GPIO inputs. This means that the value read from a GPIO is a couple of clocks old, from whatever clock source feeds those synchronizers. In practice, this means that in no-delay mode, we are using a value that can potentially be a bit too old and too close to the clock edge establishing the data on the other side of the link. The voltage converters we use on some systems make this worse and sensitive to things like voltage fluctuations etc... This is, we believe, the cause of occasional CRC errors encountered during heavy activity on the LPC bus. This is fixed by introducing a dummy GPIO read before the actual data read. It slows down SBEFIFO by about 15% (less than any delay primitive) and the end result is so far solid. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Reviewed-by: Christopher Bostic <cbostic@linux.vnet.ibm.com> Tested-by: Joel Stanley <joel@jms.id.au>
2018-06-12fsi/fsi-master-gpio: Reduce dpoll clocksBenjamin Herrenschmidt1-2/+3
FSI_GPIO_DPOLL_CLOCKS is the number of clocks before sending a DPOLL command after receiving a BUSY status. It should be at least tSendDelay (16 clocks). According to comments in the code, it needs to also be at least 21 clocks due to HW issues. It's currently 100 clocks which impacts performances negatively in some cases. Reduces it in half to 50 clocks which seems to still be solid. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Reviewed-by: Christopher Bostic <cbostic@linux.vnet.ibm.com> Tested-by: Joel Stanley <joel@jms.id.au>
2018-06-12fsi/fsi-master-gpio: Reduce turnaround clocksBenjamin Herrenschmidt1-1/+1
FSI_GPIO_PRIME_SLAVE_CLOCKS is the number of clocks if the "idle" phase between the end of a response and the beginning of the next one. It corresponds to tSendDelay in the FSI specification. The default value in the slave is 16 clocks. 100 is way overkill and significantly reduces the driver performance. This changes it to 20 (which gives the HW a bit of margin still just in case). Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Reviewed-by: Christopher Bostic <cbostic@linux.vnet.ibm.com> Tested-by: Joel Stanley <joel@jms.id.au>
2018-06-12fsi/fsi-master-gpio: Add "no-gpio-delays" optionBenjamin Herrenschmidt1-4/+16
This adds support for an optional device-tree property that makes the driver skip all the delays around clocking the GPIOs and set it in the device-tree of common POWER9 based OpenPower platforms. This useful on chips like the AST2500 where the GPIO block is running at a fairly low clock frequency (25Mhz typically). In this case, the delays are unnecessary and due to the low precision of the timers, actually quite harmful in terms of performance. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Reviewed-by: Christopher Bostic <cbostic@linux.vnet.ibm.com> Tested-by: Joel Stanley <joel@jms.id.au>
2018-06-12fsi/fsi-master-gpio: Sample input data on different clock phaseBenjamin Herrenschmidt1-3/+5
We currently sample the input data right after we toggle the clock low, then high. The slave establishes the data on the rising edge, so this is not ideal. We should sample it on the low phase instead. This currently works because we have an extra delay, but subsequent patches will remove it. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Reviewed-by: Christopher Bostic <cbostic@linux.vnet.ibm.com> Tested-by: Joel Stanley <joel@jms.id.au>
2018-06-12fsi: gpio: Use a mutex to protect transfersJeremy Kerr1-22/+64
Reduce time spent with interrupts disabled by limiting the critical sections to bitbanging FSI symbols. We only need to ensure exclusive use of the bus for an entire transfer, not that the transfer be performed in atomic context. Signed-off-by: Jeremy Kerr <jk@ozlabs.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Tested-by: Joel Stanley <joel@jms.id.au>
2018-06-12fsi: gpio: Remove unused 'id' variableAndrew Jeffery1-2/+1
Signed-off-by: Andrew Jeffery <andrew@aj.id.au> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Tested-by: Joel Stanley <joel@jms.id.au>
2018-06-12fsi: gpio: Trace busy countAndrew Jeffery1-0/+3
An observation from trace output of the existing FSI tracepoints was that the remote device was sometimes reporting as busy. Add a new tracepoint reporting the busy count in order to get a better grip on how often this is the case. Signed-off-by: Andrew Jeffery <andrew@aj.id.au> Acked-by: Eddie James <eajames@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Tested-by: Joel Stanley <joel@jms.id.au>
2018-03-14fsi: Match fsi slaves and engines to available dt nodesJeremy Kerr1-0/+4
This change populates device tree nodes for scanned FSI slaves and engines. If the master populates ->of_node of the FSI master device, we'll look for matching slaves, and under those slaves we'll look for matching engines. This means that FSI drivers will have their ->of_node pointer populated if there's a corresponding DT node, which they can use for further device discover. Presence of device tree nodes is optional, and only required for fsi device drivers that need extra properties, or subordinate devices, to be enumerated. Signed-off-by: Jeremy Kerr <jk@ozlabs.org> Signed-off-by: Joel Stanley <joel@jms.id.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-03-14fsi: master-gpio: Add external modeJeremy Kerr1-2/+76
This change introduces an 'external mode' for GPIO-based FSI masters, allowing the clock and data lines to be driven by an external source. For example, external mode is selected by a user when an external debug device is attached to the FSI pins. To do this, we need to set specific states for the trans, mux and enable GPIOs, and prevent access to clk & data from the FSI core code (by returning EBUSY). External mode is controlled by a sysfs attribute, so add the relevant information to Documentation/ABI/ Signed-off-by: Jeremy Kerr <jk@ozlabs.org> Reviewed-by: Joel Stanley <joel@jms.id.au> Signed-off-by: Joel Stanley <joel@jms.id.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-03-14fsi: master-gpio: Add locking during break and link enableJeremy Kerr1-0/+7
Currently, we perform GPIO accesses in fsi_master_gpio_break and fsi_master_link_enable, without holding cmd_lock. This change adds the appropriate locking. Signed-off-by: Jeremy Kerr <jk@ozlabs.org> Reviewed-by: Joel Stanley <joel@jms.id.au> Reviewed-by: Christopher Bostic <clbostic@linux.vnet.ibm.com> Signed-off-by: Joel Stanley <joel@jms.id.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-06-09drivers/fsi: Use asynchronous slave modeJeremy Kerr1-0/+1
For slaves that are behind a software-clocked master, we want FSI CFAMs to run asynchronously to the FSI clock, so set up our slaves to be in async mode. Signed-off-by: Jeremy Kerr <jk@ozlabs.org> Signed-off-by: Christopher Bostic <cbostic@linux.vnet.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-06-09drivers/fsi/gpio: Add tracepoints for GPIO masterJeremy Kerr1-0/+9
Trace low level input/output GPIO operations. Signed-off-by: Jeremy Kerr <jk@ozlabs.org> Signed-off-by: Christopher Bostic <cbostic@linux.vnet.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-06-09drivers/fsi: Add GPIO based FSI masterChristopher Bostic1-0/+594
Implement a FSI master using GPIO. Will generate FSI protocol for read and write commands to particular addresses. Sends master command and waits for and decodes a slave response. Includes changes from Edward A. James <eajames@us.ibm.com> and Jeremy Kerr <jk@ozlabs.org>. Signed-off-by: Edward A. James <eajames@us.ibm.com> Signed-off-by: Jeremy Kerr <jk@ozlabs.org> Signed-off-by: Christopher Bostic <cbostic@linux.vnet.ibm.com> Signed-off-by: Joel Stanley <joel@jms.id.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.