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|
/* SPDX-License-Identifier: GPL-2.0-or-later */
/* Copyright (C) 2019 IBM Corp. */
#ifndef ASPEED_PINMUX_H
#define ASPEED_PINMUX_H
#include <linux/regmap.h>
#include <stdbool.h>
/*
* The ASPEED SoCs provide typically more than 200 pins for GPIO and other
* functions. The SoC function enabled on a pin is determined on a priority
* basis where a given pin can provide a number of different signal types.
*
* The signal active on a pin is described by both a priority level and
* compound logical expressions involving multiple operators, registers and
* bits. Some difficulty arises as the pin's function bit masks for each
* priority level are frequently not the same (i.e. cannot just flip a bit to
* change from a high to low priority signal), or even in the same register.
* Further, not all signals can be unmuxed, as some expressions depend on
* values in the hardware strapping register (which may be treated as
* read-only).
*
* SoC Multi-function Pin Expression Examples
* ------------------------------------------
*
* Here are some sample mux configurations from the AST2400 and AST2500
* datasheets to illustrate the corner cases, roughly in order of least to most
* corner. The signal priorities are in decending order from P0 (highest).
*
* D6 is a pin with a single function (beside GPIO); a high priority signal
* that participates in one function:
*
* Ball | Default | P0 Signal | P0 Expression | P1 Signal | P1 Expression | Other
* -----+---------+-----------+-----------------------------+-----------+---------------+----------
* D6 GPIOA0 MAC1LINK SCU80[0]=1 GPIOA0
* -----+---------+-----------+-----------------------------+-----------+---------------+----------
*
* C5 is a multi-signal pin (high and low priority signals). Here we touch
* different registers for the different functions that enable each signal:
*
* -----+---------+-----------+-----------------------------+-----------+---------------+----------
* C5 GPIOA4 SCL9 SCU90[22]=1 TIMER5 SCU80[4]=1 GPIOA4
* -----+---------+-----------+-----------------------------+-----------+---------------+----------
*
* E19 is a single-signal pin with two functions that influence the active
* signal. In this case both bits have the same meaning - enable a dedicated
* LPC reset pin. However it's not always the case that the bits in the
* OR-relationship have the same meaning.
*
* -----+---------+-----------+-----------------------------+-----------+---------------+----------
* E19 GPIOB4 LPCRST# SCU80[12]=1 | Strap[14]=1 GPIOB4
* -----+---------+-----------+-----------------------------+-----------+---------------+----------
*
* For example, pin B19 has a low-priority signal that's enabled by two
* distinct SoC functions: A specific SIOPBI bit in register SCUA4, and an ACPI
* bit in the STRAP register. The ACPI bit configures signals on pins in
* addition to B19. Both of the low priority functions as well as the high
* priority function must be disabled for GPIOF1 to be used.
*
* Ball | Default | P0 Signal | P0 Expression | P1 Signal | P1 Expression | Other
* -----+---------+-----------+-----------------------------------------+-----------+----------------------------------------+----------
* B19 GPIOF1 NDCD4 SCU80[25]=1 SIOPBI# SCUA4[12]=1 | Strap[19]=0 GPIOF1
* -----+---------+-----------+-----------------------------------------+-----------+----------------------------------------+----------
*
* For pin E18, the SoC ANDs the expected state of three bits to determine the
* pin's active signal:
*
* * SCU3C[3]: Enable external SOC reset function
* * SCU80[15]: Enable SPICS1# or EXTRST# function pin
* * SCU90[31]: Select SPI interface CS# output
*
* -----+---------+-----------+-----------------------------------------+-----------+----------------------------------------+----------
* E18 GPIOB7 EXTRST# SCU3C[3]=1 & SCU80[15]=1 & SCU90[31]=0 SPICS1# SCU3C[3]=1 & SCU80[15]=1 & SCU90[31]=1 GPIOB7
* -----+---------+-----------+-----------------------------------------+-----------+----------------------------------------+----------
*
* (Bits SCU3C[3] and SCU80[15] appear to only be used in the expressions for
* selecting the signals on pin E18)
*
* Pin T5 is a multi-signal pin with a more complex configuration:
*
* Ball | Default | P0 Signal | P0 Expression | P1 Signal | P1 Expression | Other
* -----+---------+-----------+------------------------------+-----------+---------------+----------
* T5 GPIOL1 VPIDE SCU90[5:4]!=0 & SCU84[17]=1 NDCD1 SCU84[17]=1 GPIOL1
* -----+---------+-----------+------------------------------+-----------+---------------+----------
*
* The high priority signal configuration is best thought of in terms of its
* exploded form, with reference to the SCU90[5:4] bits:
*
* * SCU90[5:4]=00: disable
* * SCU90[5:4]=01: 18 bits (R6/G6/B6) video mode.
* * SCU90[5:4]=10: 24 bits (R8/G8/B8) video mode.
* * SCU90[5:4]=11: 30 bits (R10/G10/B10) video mode.
*
* Re-writing:
*
* -----+---------+-----------+------------------------------+-----------+---------------+----------
* T5 GPIOL1 VPIDE (SCU90[5:4]=1 & SCU84[17]=1) NDCD1 SCU84[17]=1 GPIOL1
* | (SCU90[5:4]=2 & SCU84[17]=1)
* | (SCU90[5:4]=3 & SCU84[17]=1)
* -----+---------+-----------+------------------------------+-----------+---------------+----------
*
* For reference the SCU84[17] bit configure the "UART1 NDCD1 or Video VPIDE
* function pin", where the signal itself is determined by whether SCU94[5:4]
* is disabled or in one of the 18, 24 or 30bit video modes.
*
* Other video-input-related pins require an explicit state in SCU90[5:4], e.g.
* W1 and U5:
*
* -----+---------+-----------+------------------------------+-----------+---------------+----------
* W1 GPIOL6 VPIB0 SCU90[5:4]=3 & SCU84[22]=1 TXD1 SCU84[22]=1 GPIOL6
* U5 GPIOL7 VPIB1 SCU90[5:4]=3 & SCU84[23]=1 RXD1 SCU84[23]=1 GPIOL7
* -----+---------+-----------+------------------------------+-----------+---------------+----------
*
* The examples of T5 and W1 are particularly fertile, as they also demonstrate
* that despite operating as part of the video input bus each signal needs to
* be enabled individually via it's own SCU84 (in the cases of T5 and W1)
* register bit. This is a little crazy if the bus doesn't have optional
* signals, but is used to decent effect with some of the UARTs where not all
* signals are required. However, this isn't done consistently - UART1 is
* enabled on a per-pin basis, and by contrast, all signals for UART6 are
* enabled by a single bit.
*
* Further, the high and low priority signals listed in the table above share
* a configuration bit. The VPI signals should operate in concert in a single
* function, but the UART signals should retain the ability to be configured
* independently. This pushes the implementation down the path of tagging a
* signal's expressions with the function they participate in, rather than
* defining masks affecting multiple signals per function. The latter approach
* fails in this instance where applying the configuration for the UART pin of
* interest will stomp on the state of other UART signals when disabling the
* VPI functions on the current pin.
*
* Ball | Default | P0 Signal | P0 Expression | P1 Signal | P1 Expression | Other
* -----+------------+-----------+---------------------------+-----------+---------------+------------
* A12 RGMII1TXCK GPIOT0 SCUA0[0]=1 RMII1TXEN Strap[6]=0 RGMII1TXCK
* B12 RGMII1TXCTL GPIOT1 SCUA0[1]=1 – Strap[6]=0 RGMII1TXCTL
* -----+------------+-----------+---------------------------+-----------+---------------+------------
*
* A12 demonstrates that the "Other" signal isn't always GPIO - in this case
* GPIOT0 is a high-priority signal and RGMII1TXCK is Other. Thus, GPIO
* should be treated like any other signal type with full function expression
* requirements, and not assumed to be the default case. Separately, GPIOT0 and
* GPIOT1's signal descriptor bits are distinct, therefore we must iterate all
* pins in the function's group to disable the higher-priority signals such
* that the signal for the function of interest is correctly enabled.
*
* Finally, three priority levels aren't always enough; the AST2500 brings with
* it 18 pins of five priority levels, however the 18 pins only use three of
* the five priority levels.
*
* Ultimately the requirement to control pins in the examples above drive the
* design:
*
* * Pins provide signals according to functions activated in the mux
* configuration
*
* * Pins provide up to five signal types in a priority order
*
* * For priorities levels defined on a pin, each priority provides one signal
*
* * Enabling lower priority signals requires higher priority signals be
* disabled
*
* * A function represents a set of signals; functions are distinct if their
* sets of signals are not equal
*
* * Signals participate in one or more functions
*
* * A function is described by an expression of one or more signal
* descriptors, which compare bit values in a register
*
* * A signal expression is the smallest set of signal descriptors whose
* comparisons must evaluate 'true' for a signal to be enabled on a pin.
*
* * A signal participating in a function is active on a pin if evaluating all
* signal descriptors in the pin's signal expression for the function yields
* a 'true' result
*
* * A signal at a given priority on a given pin is active if any of the
* functions in which the signal participates are active, and no higher
* priority signal on the pin is active
*
* * GPIO is configured per-pin
*
* And so:
*
* * To disable a signal, any function(s) activating the signal must be
* disabled
*
* * Each pin must know the signal expressions of functions in which it
* participates, for the purpose of enabling the Other function. This is done
* by deactivating all functions that activate higher priority signals on the
* pin.
*
* As a concrete example:
*
* * T5 provides three signals types: VPIDE, NDCD1 and GPIO
*
* * The VPIDE signal participates in 3 functions: VPI18, VPI24 and VPI30
*
* * The NDCD1 signal participates in just its own NDCD1 function
*
* * VPIDE is high priority, NDCD1 is low priority, and GPIOL1 is the least
* prioritised
*
* * The prerequisit for activating the NDCD1 signal is that the VPI18, VPI24
* and VPI30 functions all be disabled
*
* * Similarly, all of VPI18, VPI24, VPI30 and NDCD1 functions must be disabled
* to provide GPIOL6
*
* Considerations
* --------------
*
* If pinctrl allows us to allocate a pin we can configure a function without
* concern for the function of already allocated pins, if pin groups are
* created with respect to the SoC functions in which they participate. This is
* intuitive, but it did not feel obvious from the bit/pin relationships.
*
* Conversely, failing to allocate all pins in a group indicates some bits (as
* well as pins) required for the group's configuration will already be in use,
* likely in a way that's inconsistent with the requirements of the failed
* group.
*
* Implementation
* --------------
*
* Beyond the documentation below the various structures and helper macros that
* allow the implementation to hang together are defined. The macros are fairly
* dense, so below we walk through some raw examples of the configuration
* tables in an effort to clarify the concepts.
*
* The complexity of configuring the mux combined with the scale of the pins
* and functions was a concern, so the table design along with the macro jungle
* is an attempt to address it. The rough principles of the approach are:
*
* 1. Use a data-driven solution rather than embedding state into code
* 2. Minimise editing to the specifics of the given mux configuration
* 3. Detect as many errors as possible at compile time
*
* Addressing point 3 leads to naming of symbols in terms of the four
* properties associated with a given mux configuration: The pin, the signal,
* the group and the function. In this way copy/paste errors cause duplicate
* symbols to be defined, which prevents successful compilation. Failing to
* properly parent the tables leads to unused symbol warnings, and use of
* designated initialisers and additional warnings ensures that there are
* no override errors in the pin, group and function arrays.
*
* Addressing point 2 drives the development of the macro jungle, as it
* centralises the definition noise at the cost of taking some time to
* understand.
*
* Here's a complete, concrete "pre-processed" example of the table structures
* used to describe the D6 ball from the examples above:
*
* ```
* static const struct aspeed_sig_desc sig_descs_MAC1LINK_MAC1LINK[] = {
* {
* .ip = ASPEED_IP_SCU,
* .reg = 0x80,
* .mask = BIT(0),
* .enable = 1,
* .disable = 0
* },
* };
*
* static const struct aspeed_sig_expr sig_expr_MAC1LINK_MAC1LINK = {
* .signal = "MAC1LINK",
* .function = "MAC1LINK",
* .ndescs = ARRAY_SIZE(sig_descs_MAC1LINK_MAC1LINK),
* .descs = &(sig_descs_MAC1LINK_MAC1LINK)[0],
* };
*
* static const struct aspeed_sig_expr *sig_exprs_MAC1LINK_MAC1LINK[] = {
* &sig_expr_MAC1LINK_MAC1LINK,
* NULL,
* };
*
* static const struct aspeed_sig_desc sig_descs_GPIOA0_GPIOA0[] = { };
*
* static const struct aspeed_sig_expr sig_expr_GPIOA0_GPIOA0 = {
* .signal = "GPIOA0",
* .function = "GPIOA0",
* .ndescs = ARRAY_SIZE(sig_descs_GPIOA0_GPIOA0),
* .descs = &(sig_descs_GPIOA0_GPIOA0)[0],
* };
*
* static const struct aspeed_sig_expr *sig_exprs_GPIOA0_GPIOA0[] = {
* &sig_expr_GPIOA0_GPIOA0,
* NULL
* };
*
* static const struct aspeed_sig_expr **pin_exprs_0[] = {
* sig_exprs_MAC1LINK_MAC1LINK,
* sig_exprs_GPIOA0_GPIOA0,
* NULL
* };
*
* static const struct aspeed_pin_desc pin_0 = { "0", (&pin_exprs_0[0]) };
* static const int group_pins_MAC1LINK[] = { 0 };
* static const char *func_groups_MAC1LINK[] = { "MAC1LINK" };
*
* static struct pinctrl_pin_desc aspeed_g4_pins[] = {
* [0] = { .number = 0, .name = "D6", .drv_data = &pin_0 },
* };
*
* static const struct aspeed_pin_group aspeed_g4_groups[] = {
* {
* .name = "MAC1LINK",
* .pins = &(group_pins_MAC1LINK)[0],
* .npins = ARRAY_SIZE(group_pins_MAC1LINK),
* },
* };
*
* static const struct aspeed_pin_function aspeed_g4_functions[] = {
* {
* .name = "MAC1LINK",
* .groups = &func_groups_MAC1LINK[0],
* .ngroups = ARRAY_SIZE(func_groups_MAC1LINK),
* },
* };
* ```
*
* At the end of the day much of the above code is compressed into the
* following two lines:
*
* ```
* #define D6 0
* SSSF_PIN_DECL(D6, GPIOA0, MAC1LINK, SIG_DESC_SET(SCU80, 0));
* ```
*
* The two examples below show just the differences from the example above.
*
* Ball E18 demonstrates a function, EXTRST, that requires multiple descriptors
* be set for it to be muxed:
*
* ```
* static const struct aspeed_sig_desc sig_descs_EXTRST_EXTRST[] = {
* {
* .ip = ASPEED_IP_SCU,
* .reg = 0x3C,
* .mask = BIT(3),
* .enable = 1,
* .disable = 0
* },
* {
* .ip = ASPEED_IP_SCU,
* .reg = 0x80,
* .mask = BIT(15),
* .enable = 1,
* .disable = 0
* },
* {
* .ip = ASPEED_IP_SCU,
* .reg = 0x90,
* .mask = BIT(31),
* .enable = 0,
* .disable = 1
* },
* };
*
* static const struct aspeed_sig_expr sig_expr_EXTRST_EXTRST = {
* .signal = "EXTRST",
* .function = "EXTRST",
* .ndescs = ARRAY_SIZE(sig_descs_EXTRST_EXTRST),
* .descs = &(sig_descs_EXTRST_EXTRST)[0],
* };
* ...
* ```
*
* For ball E19, we have multiple functions enabling a single signal, LPCRST#.
* The data structures look like:
*
* static const struct aspeed_sig_desc sig_descs_LPCRST_LPCRST[] = {
* {
* .ip = ASPEED_IP_SCU,
* .reg = 0x80,
* .mask = BIT(12),
* .enable = 1,
* .disable = 0
* },
* };
*
* static const struct aspeed_sig_expr sig_expr_LPCRST_LPCRST = {
* .signal = "LPCRST",
* .function = "LPCRST",
* .ndescs = ARRAY_SIZE(sig_descs_LPCRST_LPCRST),
* .descs = &(sig_descs_LPCRST_LPCRST)[0],
* };
*
* static const struct aspeed_sig_desc sig_descs_LPCRST_LPCRSTS[] = {
* {
* .ip = ASPEED_IP_SCU,
* .reg = 0x70,
* .mask = BIT(14),
* .enable = 1,
* .disable = 0
* },
* };
*
* static const struct aspeed_sig_expr sig_expr_LPCRST_LPCRSTS = {
* .signal = "LPCRST",
* .function = "LPCRSTS",
* .ndescs = ARRAY_SIZE(sig_descs_LPCRST_LPCRSTS),
* .descs = &(sig_descs_LPCRST_LPCRSTS)[0],
* };
*
* static const struct aspeed_sig_expr *sig_exprs_LPCRST_LPCRST[] = {
* &sig_expr_LPCRST_LPCRST,
* &sig_expr_LPCRST_LPCRSTS,
* NULL,
* };
* ...
* ```
*
* Both expressions listed in the sig_exprs_LPCRST_LPCRST array need to be set
* to disabled for the associated GPIO to be muxed.
*
*/
#define ASPEED_IP_SCU 0
#define ASPEED_IP_GFX 1
#define ASPEED_IP_LPC 2
#define ASPEED_NR_PINMUX_IPS 3
/**
* A signal descriptor, which describes the register, bits and the
* enable/disable values that should be compared or written.
*
* @ip: The IP block identifier, used as an index into the regmap array in
* struct aspeed_pinctrl_data
* @reg: The register offset with respect to the base address of the IP block
* @mask: The mask to apply to the register. The lowest set bit of the mask is
* used to derive the shift value.
* @enable: The value that enables the function. Value should be in the LSBs,
* not at the position of the mask.
* @disable: The value that disables the function. Value should be in the
* LSBs, not at the position of the mask.
*/
struct aspeed_sig_desc {
unsigned int ip;
unsigned int reg;
u32 mask;
u32 enable;
u32 disable;
};
/**
* Describes a signal expression. The expression is evaluated by ANDing the
* evaluation of the descriptors.
*
* @signal: The signal name for the priority level on the pin. If the signal
* type is GPIO, then the signal name must begin with the string
* "GPIO", e.g. GPIOA0, GPIOT4 etc.
* @function: The name of the function the signal participates in for the
* associated expression
* @ndescs: The number of signal descriptors in the expression
* @descs: Pointer to an array of signal descriptors that comprise the
* function expression
*/
struct aspeed_sig_expr <
|