Several pinconf parameters have a fairly straight-forward mapping onto
the Aspeed pin controller. These include management of pull-down bias,
drive-strength, and some debounce configuration.
Pin biasing largely is managed on a per-GPIO-bank basis, aside from the
ADC and RMII/RGMII pins. As the bias configuration for each pin in a
bank maps onto a single per-bank bit, configuration tables will be
introduced to describe the ranges of pins and the supported pinconf
parameter. The use of tables also helps with the sparse support of
pinconf properties, and the fact that not all GPIO banks support
biasing or drive-strength configuration.
Further, as the pin controller uses a consistent approach for bias and
drive strength configuration at the register level, a second table is
defined for looking up the the bit-state required to enable or query the
provided configuration.
Testing for pinctrl-aspeed-g4 was performed on an OpenPOWER Palmetto
system, and pinctrl-aspeed-g5 on an AST2500EVB as well as under QEMU.
The test method was to set the appropriate bits via devmem and verify
the result through the controller's pinconf-pins debugfs file. This
simultaneously validates the get() path and half of the set() path. The
remainder of the set() path was validated by configuring a handful of
pins via the devicetree with the supported pinconf properties and
verifying the appropriate registers were touched.
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Port D and port E GPIO loopback modes are commonly enabled via hardware
straps for use with front-panel buttons. When the BMC is powered
off or fails to boot, the front-panel buttons are directly connected to
the host chipset via the loopback to allow direct power-on and reset
control. Once the BMC has booted, the loopback mode must be disabled for
the BMC to take over control of host power-on and reset.
Disabling these loopback modes requires writing to the hardware strap
register which violates the current design of assuming the system
designer chose the strap settings for a specific reason and they should
be treated as read-only. Only the two bits of the strap register related
to these loopback modes are allowed to be written and comments have been
added to explain why.
Signed-off-by: Rick Altherr <raltherr@google.com>
Acked-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
The System Control Unit IP block in the Aspeed SoCs is typically where
the pinmux configuration is found, but not always. A number of pins
depend on state in one of LPC Host Control (LHC) or SoC Display
Controller (GFX) IP blocks, so the Aspeed pinmux drivers should have the
means to adjust these as necessary.
We use syscon to cast a regmap over the GFX and LPC blocks, which is
used as an arbitration layer between the relevant driver and the pinctrl
subsystem. The regmaps are then exposed to the SoC-specific pinctrl
drivers by phandles in the devicetree, and are selected during a mux
request by querying a new 'ip' member in struct aspeed_sig_desc.
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Consider a scenario with one pin P that has two signals A and B, where A
is defined to be higher priority than B: That is, if the mux IP is in a
state that would consider both A and B to be active on P, then A will be
the active signal.
To instead configure B as the active signal we must configure the mux so
that A is inactive. The mux state for signals can be described by
logical operations on one or more bits from one or more registers (a
"signal expression"), which in some cases leads to aliased mux states for
a particular signal. Further, signals described by multi-bit bitfields
often do not only need to record the states that would make them active
(the "enable" expressions), but also the states that makes them inactive
(the "disable" expressions). All of this combined leads to four possible
states for a signal:
1. A signal is active with respect to an "enable" expression
2. A signal is not active with respect to an "enable" expression
3. A signal is inactive with respect to a "disable" expression
4. A signal is not inactive with respect to a "disable" expression
In the case of P, if we are looking to activate B without explicitly
having configured A it's enough to consider A inactive if all of A's
"enable" signal expressions evaluate to "not active". If any evaluate to
"active" then the corresponding "disable" states must be applied so it
becomes inactive.
For example, on the AST2400 the pins composing GPIO bank H provide
signals ROMD8 through ROMD15 (high priority) and those for UART6 (low
priority). The mux states for ROMD8 through ROMD15 are aliased, i.e.
there are two mux states that result in the respective signals being
configured:
A. SCU90[6]=1
B. Strap[4,1:0]=100
Further, the second mux state is a 3-bit bitfield that explicitly
defines the enabled state but the disabled state is implicit, i.e. if
Strap[4,1:0] is not exactly "100" then ROMD8 through ROMD15 are not
considered active. This requires the mux function evaluation logic to
use approach 2. above, however the existing code was using approach 3.
The problem was brought to light on the Palmetto machines where the
strap register value is 0x120ce416, and prevented GPIO requests in bank
H from succeeding despite the hardware being in a position to allow
them.
Fixes: 318398c09a8d ("pinctrl: Add core pinctrl support for Aspeed SoCs")
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
The newly added aspeed driver tries to check for a negative return
value from a pinctrl function, but stores the intermediate value in
a 'bool' variable, which cannot work:
drivers/pinctrl/aspeed/pinctrl-aspeed.c: In function 'aspeed_sig_expr_set':
drivers/pinctrl/aspeed/pinctrl-aspeed.c:192:11: error: comparison of constant '0' with boolean expression is always false [-Werror=bool-compare]
This slightly reworks the logic to use an explicit comparison with zero
before assigning to the temporary variable.
Reported-by: Colin King <colin.king@canonical.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
The Aspeed SoCs typically provide more than 200 pins for GPIO and other
functions. The signal enabled on a pin is determined on a priority
basis, where a given pin can provide a number of different signal types.
In addition to the priority levels, the Aspeed pin controllers describe
the signal active on a pin by compound logical expressions involving
multiple operators, registers and bits. Some difficulty arises as a
pin's function bit masks for each priority level are frequently not the
same (i.e. we cannot just flip a bit to change from a high to low
priority signal), or even in the same register(s). Some configuration
bits affect multiple pins, while in other cases the signals for a bus
must each be enabled individually.
Together, these features give rise to some complexity in the
implementation. A more complete description of the complexities is
provided in the associated header file.
The patch doesn't implement pinctrl/pinmux/pinconf for any particular
Aspeed SoC, rather it adds the framework for defining pinmux
configurations.
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
