pinctrl: Add core support for Aspeed SoCs
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>
diff --git a/drivers/pinctrl/aspeed/pinctrl-aspeed.c b/drivers/pinctrl/aspeed/pinctrl-aspeed.c
new file mode 100644
index 0000000..7d461fc
--- /dev/null
+++ b/drivers/pinctrl/aspeed/pinctrl-aspeed.c
@@ -0,0 +1,498 @@
+/*
+ * Copyright (C) 2016 IBM Corp.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/mfd/syscon.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include "../core.h"
+#include "pinctrl-aspeed.h"
+
+int aspeed_pinctrl_get_groups_count(struct pinctrl_dev *pctldev)
+{
+ struct aspeed_pinctrl_data *pdata = pinctrl_dev_get_drvdata(pctldev);
+
+ return pdata->ngroups;
+}
+
+const char *aspeed_pinctrl_get_group_name(struct pinctrl_dev *pctldev,
+ unsigned int group)
+{
+ struct aspeed_pinctrl_data *pdata = pinctrl_dev_get_drvdata(pctldev);
+
+ return pdata->groups[group].name;
+}
+
+int aspeed_pinctrl_get_group_pins(struct pinctrl_dev *pctldev,
+ unsigned int group, const unsigned int **pins,
+ unsigned int *npins)
+{
+ struct aspeed_pinctrl_data *pdata = pinctrl_dev_get_drvdata(pctldev);
+
+ *pins = &pdata->groups[group].pins[0];
+ *npins = pdata->groups[group].npins;
+
+ return 0;
+}
+
+void aspeed_pinctrl_pin_dbg_show(struct pinctrl_dev *pctldev,
+ struct seq_file *s, unsigned int offset)
+{
+ seq_printf(s, " %s", dev_name(pctldev->dev));
+}
+
+int aspeed_pinmux_get_fn_count(struct pinctrl_dev *pctldev)
+{
+ struct aspeed_pinctrl_data *pdata = pinctrl_dev_get_drvdata(pctldev);
+
+ return pdata->nfunctions;
+}
+
+const char *aspeed_pinmux_get_fn_name(struct pinctrl_dev *pctldev,
+ unsigned int function)
+{
+ struct aspeed_pinctrl_data *pdata = pinctrl_dev_get_drvdata(pctldev);
+
+ return pdata->functions[function].name;
+}
+
+int aspeed_pinmux_get_fn_groups(struct pinctrl_dev *pctldev,
+ unsigned int function,
+ const char * const **groups,
+ unsigned int * const num_groups)
+{
+ struct aspeed_pinctrl_data *pdata = pinctrl_dev_get_drvdata(pctldev);
+
+ *groups = pdata->functions[function].groups;
+ *num_groups = pdata->functions[function].ngroups;
+
+ return 0;
+}
+
+static inline void aspeed_sig_desc_print_val(
+ const struct aspeed_sig_desc *desc, bool enable, u32 rv)
+{
+ pr_debug("SCU%x[0x%08x]=0x%x, got 0x%x from 0x%08x\n", desc->reg,
+ desc->mask, enable ? desc->enable : desc->disable,
+ (rv & desc->mask) >> __ffs(desc->mask), rv);
+}
+
+/**
+ * Query the enabled or disabled state of a signal descriptor
+ *
+ * @desc: The signal descriptor of interest
+ * @enabled: True to query the enabled state, false to query disabled state
+ * @regmap: The SCU regmap instance
+ *
+ * @return True if the descriptor's bitfield is configured to the state
+ * selected by @enabled, false otherwise
+ *
+ * Evaluation of descriptor state is non-trivial in that it is not a binary
+ * outcome: The bitfields can be greater than one bit in size and thus can take
+ * a value that is neither the enabled nor disabled state recorded in the
+ * descriptor (typically this means a different function to the one of interest
+ * is enabled). Thus we must explicitly test for either condition as required.
+ */
+static bool aspeed_sig_desc_eval(const struct aspeed_sig_desc *desc,
+ bool enabled, struct regmap *map)
+{
+ unsigned int raw;
+ u32 want;
+
+ if (regmap_read(map, desc->reg, &raw) < 0)
+ return false;
+
+ aspeed_sig_desc_print_val(desc, enabled, raw);
+ want = enabled ? desc->enable : desc->disable;
+
+ return ((raw & desc->mask) >> __ffs(desc->mask)) == want;
+}
+
+/**
+ * Query the enabled or disabled state for a mux function's signal on a pin
+ *
+ * @expr: An expression controlling the signal for a mux function on a pin
+ * @enabled: True to query the enabled state, false to query disabled state
+ * @regmap: The SCU regmap instance
+ *
+ * @return True if the expression composed by @enabled evaluates true, false
+ * otherwise
+ *
+ * A mux function is enabled or disabled if the function's signal expression
+ * for each pin in the function's pin group evaluates true for the desired
+ * state. An signal expression evaluates true if all of its associated signal
+ * descriptors evaluate true for the desired state.
+ *
+ * If an expression's state is described by more than one bit, either through
+ * multi-bit bitfields in a single signal descriptor or through multiple signal
+ * descriptors of a single bit then it is possible for the expression to be in
+ * neither the enabled nor disabled state. Thus we must explicitly test for
+ * either condition as required.
+ */
+static bool aspeed_sig_expr_eval(const struct aspeed_sig_expr *expr,
+ bool enabled, struct regmap *map)
+{
+ int i;
+
+ for (i = 0; i < expr->ndescs; i++) {
+ const struct aspeed_sig_desc *desc = &expr->descs[i];
+
+ if (!aspeed_sig_desc_eval(desc, enabled, map))
+ return false;
+ }
+
+ return true;
+}
+
+/**
+ * Configure a pin's signal by applying an expression's descriptor state for
+ * all descriptors in the expression.
+ *
+ * @expr: The expression associated with the function whose signal is to be
+ * configured
+ * @enable: true to enable an function's signal through a pin's signal
+ * expression, false to disable the function's signal
+ * @map: The SCU's regmap instance for pinmux register access.
+ *
+ * @return true if the expression is configured as requested, false otherwise
+ */
+static bool aspeed_sig_expr_set(const struct aspeed_sig_expr *expr,
+ bool enable, struct regmap *map)
+{
+ int i;
+ bool ret;
+
+ ret = aspeed_sig_expr_eval(expr, enable, map);
+ if (ret)
+ return ret;
+
+ for (i = 0; i < expr->ndescs; i++) {
+ const struct aspeed_sig_desc *desc = &expr->descs[i];
+ u32 pattern = enable ? desc->enable : desc->disable;
+
+ /*
+ * Strap registers are configured in hardware or by early-boot
+ * firmware. Treat them as read-only despite that we can write
+ * them. This may mean that certain functions cannot be
+ * deconfigured and is the reason we re-evaluate after writing
+ * all descriptor bits.
+ */
+ if (desc->reg == HW_STRAP1 || desc->reg == HW_STRAP2)
+ continue;
+
+ ret = regmap_update_bits(map, desc->reg, desc->mask,
+ pattern << __ffs(desc->mask));
+
+ if (ret < 0)
+ return false;
+ }
+
+ return aspeed_sig_expr_eval(expr, enable, map);
+}
+
+static bool aspeed_sig_expr_enable(const struct aspeed_sig_expr *expr,
+ struct regmap *map)
+{
+ return aspeed_sig_expr_set(expr, true, map);
+}
+
+static bool aspeed_sig_expr_disable(const struct aspeed_sig_expr *expr,
+ struct regmap *map)
+{
+ return aspeed_sig_expr_set(expr, false, map);
+}
+
+/**
+ * Disable a signal on a pin by disabling all provided signal expressions.
+ *
+ * @exprs: The list of signal expressions (from a priority level on a pin)
+ * @map: The SCU's regmap instance for pinmux register access.
+ *
+ * @return true if all expressions in the list are successfully disabled, false
+ * otherwise
+ */
+static bool aspeed_disable_sig(const struct aspeed_sig_expr **exprs,
+ struct regmap *map)
+{
+ bool disabled = true;
+
+ if (!exprs)
+ return true;
+
+ while (*exprs) {
+ bool ret;
+
+ ret = aspeed_sig_expr_disable(*exprs, map);
+ disabled = disabled && ret;
+
+ exprs++;
+ }
+
+ return disabled;
+}
+
+/**
+ * Search for the signal expression needed to enable the pin's signal for the
+ * requested function.
+ *
+ * @exprs: List of signal expressions (haystack)
+ * @name: The name of the requested function (needle)
+ *
+ * @return A pointer to the signal expression whose function tag matches the
+ * provided name, otherwise NULL.
+ *
+ */
+static const struct aspeed_sig_expr *aspeed_find_expr_by_name(
+ const struct aspeed_sig_expr **exprs, const char *name)
+{
+ while (*exprs) {
+ if (strcmp((*exprs)->function, name) == 0)
+ return *exprs;
+ exprs++;
+ }
+
+ return NULL;
+}
+
+static char *get_defined_attribute(const struct aspeed_pin_desc *pdesc,
+ const char *(*get)(
+ const struct aspeed_sig_expr *))
+{
+ char *found = NULL;
+ size_t len = 0;
+ const struct aspeed_sig_expr ***prios, **funcs, *expr;
+
+ prios = pdesc->prios;
+
+ while ((funcs = *prios)) {
+ while ((expr = *funcs)) {
+ const char *str = get(expr);
+ size_t delta = strlen(str) + 2;
+ char *expanded;
+
+ expanded = krealloc(found, len + delta + 1, GFP_KERNEL);
+ if (!expanded) {
+ kfree(found);
+ return expanded;
+ }
+
+ found = expanded;
+ found[len] = '\0';
+ len += delta;
+
+ strcat(found, str);
+ strcat(found, ", ");
+
+ funcs++;
+ }
+ prios++;
+ }
+
+ if (len < 2) {
+ kfree(found);
+ return NULL;
+ }
+
+ found[len - 2] = '\0';
+
+ return found;
+}
+
+static const char *aspeed_sig_expr_function(const struct aspeed_sig_expr *expr)
+{
+ return expr->function;
+}
+
+static char *get_defined_functions(const struct aspeed_pin_desc *pdesc)
+{
+ return get_defined_attribute(pdesc, aspeed_sig_expr_function);
+}
+
+static const char *aspeed_sig_expr_signal(const struct aspeed_sig_expr *expr)
+{
+ return expr->signal;
+}
+
+static char *get_defined_signals(const struct aspeed_pin_desc *pdesc)
+{
+ return get_defined_attribute(pdesc, aspeed_sig_expr_signal);
+}
+
+int aspeed_pinmux_set_mux(struct pinctrl_dev *pctldev, unsigned int function,
+ unsigned int group)
+{
+ int i;
+ const struct aspeed_pinctrl_data *pdata =
+ pinctrl_dev_get_drvdata(pctldev);
+ const struct aspeed_pin_group *pgroup = &pdata->groups[group];
+ const struct aspeed_pin_function *pfunc =
+ &pdata->functions[function];
+
+ for (i = 0; i < pgroup->npins; i++) {
+ int pin = pgroup->pins[i];
+ const struct aspeed_pin_desc *pdesc = pdata->pins[pin].drv_data;
+ const struct aspeed_sig_expr *expr = NULL;
+ const struct aspeed_sig_expr **funcs;
+ const struct aspeed_sig_expr ***prios;
+
+ if (!pdesc)
+ return -EINVAL;
+
+ prios = pdesc->prios;
+
+ if (!prios)
+ continue;
+
+ /* Disable functions at a higher priority than that requested */
+ while ((funcs = *prios)) {
+ expr = aspeed_find_expr_by_name(funcs, pfunc->name);
+
+ if (expr)
+ break;
+
+ if (!aspeed_disable_sig(funcs, pdata->map))
+ return -EPERM;
+
+ prios++;
+ }
+
+ if (!expr) {
+ char *functions = get_defined_functions(pdesc);
+ char *signals = get_defined_signals(pdesc);
+
+ pr_warn("No function %s found on pin %s (%d). Found signal(s) %s for function(s) %s\n",
+ pfunc->name, pdesc->name, pin, signals,
+ functions);
+ kfree(signals);
+ kfree(functions);
+
+ return -ENXIO;
+ }
+
+ if (!aspeed_sig_expr_enable(expr, pdata->map))
+ return -EPERM;
+ }
+
+ return 0;
+}
+
+static bool aspeed_expr_is_gpio(const struct aspeed_sig_expr *expr)
+{
+ /*
+ * The signal type is GPIO if the signal name has "GPIO" as a prefix.
+ * strncmp (rather than strcmp) is used to implement the prefix
+ * requirement.
+ *
+ * expr->signal might look like "GPIOT3" in the GPIO case.
+ */
+ return strncmp(expr->signal, "GPIO", 4) == 0;
+}
+
+static bool aspeed_gpio_in_exprs(const struct aspeed_sig_expr **exprs)
+{
+ if (!exprs)
+ return false;
+
+ while (*exprs) {
+ if (aspeed_expr_is_gpio(*exprs))
+ return true;
+ exprs++;
+ }
+
+ return false;
+}
+
+int aspeed_gpio_request_enable(struct pinctrl_dev *pctldev,
+ struct pinctrl_gpio_range *range,
+ unsigned int offset)
+{
+ const struct aspeed_pinctrl_data *pdata =
+ pinctrl_dev_get_drvdata(pctldev);
+ const struct aspeed_pin_desc *pdesc = pdata->pins[offset].drv_data;
+ const struct aspeed_sig_expr ***prios, **funcs, *expr;
+
+ if (!pdesc)
+ return -EINVAL;
+
+ prios = pdesc->prios;
+
+ if (!prios)
+ return -ENXIO;
+
+ /* Disable any functions of higher priority than GPIO */
+ while ((funcs = *prios)) {
+ if (aspeed_gpio_in_exprs(funcs))
+ break;
+
+ if (!aspeed_disable_sig(funcs, pdata->map))
+ return -EPERM;
+
+ prios++;
+ }
+
+ if (!funcs) {
+ char *signals = get_defined_signals(pdesc);
+
+ pr_warn("No GPIO signal type found on pin %s (%d). Found: %s\n",
+ pdesc->name, offset, signals);
+ kfree(signals);
+
+ return -ENXIO;
+ }
+
+ expr = *funcs;
+
+ /*
+ * Disabling all higher-priority expressions is enough to enable the
+ * lowest-priority signal type. As such it has no associated
+ * expression.
+ */
+ if (!expr)
+ return 0;
+
+ /*
+ * If GPIO is not the lowest priority signal type, assume there is only
+ * one expression defined to enable the GPIO function
+ */
+ if (!aspeed_sig_expr_enable(expr, pdata->map))
+ return -EPERM;
+
+ return 0;
+}
+
+int aspeed_pinctrl_probe(struct platform_device *pdev,
+ struct pinctrl_desc *pdesc,
+ struct aspeed_pinctrl_data *pdata)
+{
+ struct device *parent;
+ struct pinctrl_dev *pctl;
+
+ parent = pdev->dev.parent;
+ if (!parent) {
+ dev_err(&pdev->dev, "No parent for syscon pincontroller\n");
+ return -ENODEV;
+ }
+
+ pdata->map = syscon_node_to_regmap(parent->of_node);
+ if (IS_ERR(pdata->map)) {
+ dev_err(&pdev->dev, "No regmap for syscon pincontroller parent\n");
+ return PTR_ERR(pdata->map);
+ }
+
+ pctl = pinctrl_register(pdesc, &pdev->dev, pdata);
+
+ if (IS_ERR(pctl)) {
+ dev_err(&pdev->dev, "Failed to register pinctrl\n");
+ return PTR_ERR(pctl);
+ }
+
+ platform_set_drvdata(pdev, pdata);
+
+ return 0;
+}