Kconfig: Introduce the "imply" keyword

The "imply" keyword is a weak version of "select" where the target
config symbol can still be turned off, avoiding those pitfalls that come
with the "select" keyword.

This is useful e.g. with multiple drivers that want to indicate their
ability to hook into a secondary subsystem while allowing the user to
configure that subsystem out without also having to unset these drivers.

Currently, the same effect can almost be achieved with:

config DRIVER_A
	tristate

config DRIVER_B
	tristate

config DRIVER_C
	tristate

config DRIVER_D
	tristate

[...]

config SUBSYSTEM_X
	tristate
	default DRIVER_A || DRIVER_B || DRIVER_C || DRIVER_D || [...]

This is unwieldy to maintain especially with a large number of drivers.
Furthermore, there is no easy way to restrict the choice for SUBSYSTEM_X
to y or n, excluding m, when some drivers are built-in. The "select"
keyword allows for excluding m, but it excludes n as well. Hence
this "imply" keyword.  The above becomes:

config DRIVER_A
	tristate
	imply SUBSYSTEM_X

config DRIVER_B
	tristate
	imply SUBSYSTEM_X

[...]

config SUBSYSTEM_X
	tristate

This is much cleaner, and way more flexible than "select". SUBSYSTEM_X
can still be configured out, and it can be set as a module when none of
the drivers are configured in or all of them are modular.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <john.stultz@linaro.org>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Cc: Paul Bolle <pebolle@tiscali.nl>
Cc: linux-kbuild@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: Michal Marek <mmarek@suse.com>
Cc: Edward Cree <ecree@solarflare.com>
Link: http://lkml.kernel.org/r/1478841010-28605-2-git-send-email-nicolas.pitre@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Christian Lamparter <chunkeey@gmail.com>

diff --git a/config/expr.h b/config/expr.h
index 973b6f73336829a6290a0d2bb15a841086d9a18c..a73f762c48d6964e1ef7adb97bfea9e8fb471078 100644 (file)
--- a/config/expr.h
+++ b/config/expr.h
@@ -85,6 +85,7 @@ struct symbol {
        struct property *prop;
        struct expr_value dir_dep;
        struct expr_value rev_dep;
+       struct expr_value implied;
 };
 
 #define for_all_symbols(i, sym) for (i = 0; i < SYMBOL_HASHSIZE; i++) for (sym = symbol_hash[i]; sym; sym = sym->next) if (sym->type != S_OTHER)
@@ -136,6 +137,7 @@ enum prop_type {
        P_DEFAULT,  /* default y */
        P_CHOICE,   /* choice value */
        P_SELECT,   /* select BAR */
+       P_IMPLY,    /* imply BAR */
        P_RANGE,    /* range 7..100 (for a symbol) */
        P_ENV,      /* value from environment variable */
        P_SYMBOL,   /* where a symbol is defined */

diff --git a/config/menu.c b/config/menu.c
index aed678e8a77750812bb9e49b7d9e7c6e32f9eea1..e9357931b47db3fdf7f63da842a045697e038ed9 100644 (file)
--- a/config/menu.c
+++ b/config/menu.c
@@ -233,6 +233,8 @@ static void sym_check_prop(struct symbol *sym)
 {
        struct property *prop;
        struct symbol *sym2;
+       char *use;
+
        for (prop = sym->prop; prop; prop = prop->next) {
                switch (prop->type) {
                case P_DEFAULT:
@@ -252,18 +254,20 @@ static void sym_check_prop(struct symbol *sym)
                        }
                        break;
                case P_SELECT:
+               case P_IMPLY:
+                       use = prop->type == P_SELECT ? "select" : "imply";
                        sym2 = prop_get_symbol(prop);
                        if (sym->type != S_BOOLEAN && sym->type != S_TRISTATE)
                                prop_warn(prop,
-                                   "config symbol '%s' uses select, but is "
-                                   "not boolean or tristate", sym->name);
+                                   "config symbol '%s' uses %s, but is "
+                                   "not boolean or tristate", sym->name, use);
                        else if (sym2->type != S_UNKNOWN &&
                                 sym2->type != S_BOOLEAN &&
                                 sym2->type != S_TRISTATE)
                                prop_warn(prop,
-                                   "'%s' has wrong type. 'select' only "
+                                   "'%s' has wrong type. '%s' only "
                                    "accept arguments of boolean and "
-                                   "tristate type", sym2->name);
+                                   "tristate type", sym2->name, use);
                        break;
                case P_RANGE:
                        if (sym->type != S_INT && sym->type != S_HEX)
@@ -333,6 +337,10 @@ void menu_finalize(struct menu *parent)
                                        struct symbol *es = prop_get_symbol(prop);
                                        es->rev_dep.expr = expr_alloc_or(es->rev_dep.expr,
                                                        expr_alloc_and(expr_alloc_symbol(menu->sym), expr_copy(dep)));
+                               } else if (prop->type == P_IMPLY) {
+                                       struct symbol *es = prop_get_symbol(prop);
+                                       es->implied.expr = expr_alloc_or(es->implied.expr,
+                                                       expr_alloc_and(expr_alloc_symbol(menu->sym), expr_copy(dep)));
                                }
                        }
                }
@@ -612,13 +620,30 @@ static struct property *get_symbol_prop(struct symbol *sym)
        return prop;
 }
 
+static void get_symbol_props_str(struct gstr *r, struct symbol *sym,
+                                enum prop_type tok, const char *prefix)
+{
+       bool hit = false;
+       struct property *prop;
+
+       for_all_properties(sym, prop, tok) {
+               if (!hit) {
+                       str_append(r, prefix);
+                       hit = true;
+               } else
+                       str_printf(r, " && ");
+               expr_gstr_print(prop->expr, r);
+       }
+       if (hit)
+               str_append(r, "\n");
+}
+
 /*
  * head is optional and may be NULL
  */
 static void get_symbol_str(struct gstr *r, struct symbol *sym,
                    struct list_head *head)
 {
-       bool hit;
        struct property *prop;
 
        if (sym && sym->name) {
@@ -648,22 +673,20 @@ static void get_symbol_str(struct gstr *r, struct symbol *sym,
                }
        }
 
-       hit = false;
-       for_all_properties(sym, prop, P_SELECT) {
-               if (!hit) {
-                       str_append(r, "  Selects: ");
-                       hit = true;
-               } else
-                       str_printf(r, " && ");
-               expr_gstr_print(prop->expr, r);
-       }
-       if (hit)
-               str_append(r, "\n");
+       get_symbol_props_str(r, sym, P_SELECT, _("  Selects: "));
        if (sym->rev_dep.expr) {
                str_append(r, _("  Selected by: "));
                expr_gstr_print(sym->rev_dep.expr, r);
                str_append(r, "\n");
        }
+
+       get_symbol_props_str(r, sym, P_IMPLY, _("  Implies: "));
+       if (sym->implied.expr) {
+               str_append(r, _("  Implied by: "));
+               expr_gstr_print(sym->implied.expr, r);
+               str_append(r, "\n");
+       }
+
        str_append(r, "\n\n");
 }
 

diff --git a/config/symbol.c b/config/symbol.c
index 2432298487fb330d04e365fa2b1c81ed6fbba691..20136ffefb23b814fa8b300b70a07b821b3ec71f 100644 (file)
--- a/config/symbol.c
+++ b/config/symbol.c
@@ -258,6 +258,15 @@ static void sym_calc_visibility(struct symbol *sym)
                sym->rev_dep.tri = tri;
                sym_set_changed(sym);
        }
+       tri = no;
+       if (sym->implied.expr && sym->dir_dep.tri != no)
+               tri = expr_calc_value(sym->implied.expr);
+       if (tri == mod && sym_get_type(sym) == S_BOOLEAN)
+               tri = yes;
+       if (sym->implied.tri != tri) {
+               sym->implied.tri = tri;
+               sym_set_changed(sym);
+       }
 }
 
 /*
@@ -397,6 +406,10 @@ void sym_calc_value(struct symbol *sym)
                                        newval.tri = EXPR_AND(expr_calc_value(prop->expr),
                                                              prop->visible.tri);
                                }
+                               if (sym->implied.tri != no) {
+                                       sym->flags |= SYMBOL_WRITE;
+                                       newval.tri = EXPR_OR(newval.tri, sym->implied.tri);
+                               }
                        }
                calc_newval:
                        if (sym->dir_dep.tri == no && sym->rev_dep.tri != no) {
@@ -413,7 +426,8 @@ void sym_calc_value(struct symbol *sym)
                        }
                        newval.tri = EXPR_OR(newval.tri, sym->rev_dep.tri);
                }
-               if (newval.tri == mod && sym_get_type(sym) == S_BOOLEAN)
+               if (newval.tri == mod &&
+                   (sym_get_type(sym) == S_BOOLEAN || sym->implied.tri == yes))
                        newval.tri = yes;
                break;
        case S_STRING:
@@ -498,6 +512,8 @@ bool sym_tristate_within_range(struct symbol *sym, tristate val)
                return false;
        if (sym->visible <= sym->rev_dep.tri)
                return false;
+       if (sym->implied.tri == yes && val == mod)
+               return false;
        if (sym_is_choice_value(sym) && sym->visible == yes)
                return val == yes;
        return val >= sym->rev_dep.tri && val <= sym->visible;
@@ -750,6 +766,10 @@ const char *sym_get_string_default(struct symbol *sym)
        if (sym->type == S_BOOLEAN && val == mod)
                val = yes;
 
+       /* adjust the default value if this symbol is implied by another */
+       if (val < sym->implied.tri)
+               val = sym->implied.tri;
+
        switch (sym->type) {
        case S_BOOLEAN:
        case S_TRISTATE:
@@ -1352,6 +1372,8 @@ const char *prop_get_type_name(enum prop_type type)
                return "choice";
        case P_SELECT:
                return "select";
+       case P_IMPLY:
+               return "imply";
        case P_RANGE:
                return "range";
        case P_SYMBOL:

diff --git a/config/zconf.gperf b/config/zconf.gperf
index 9ce6b53d903f8cdd99fcfe2a59c52dd981b7626a..574f7b3b8c7aae5a5193d8698d23d7c48136ea3e 100644 (file)
--- a/config/zconf.gperf
+++ b/config/zconf.gperf
@@ -38,6 +38,7 @@ int,          T_TYPE,         TF_COMMAND, S_INT
 hex,           T_TYPE,         TF_COMMAND, S_HEX
 string,                T_TYPE,         TF_COMMAND, S_STRING
 select,                T_SELECT,       TF_COMMAND
+imply,         T_IMPLY,        TF_COMMAND
 range,         T_RANGE,        TF_COMMAND
 visible,       T_VISIBLE,      TF_COMMAND
 option,                T_OPTION,       TF_COMMAND

diff --git a/config/zconf.y b/config/zconf.y
index efa93e9d030a6b24f4a475c1669a167efad45c55..dfd602124b1037ea011653a30d16994bd00797d4 100644 (file)
--- a/config/zconf.y
+++ b/config/zconf.y
@@ -31,7 +31,7 @@ struct symbol *symbol_hash[SYMBOL_HASHSIZE];
 static struct menu *current_menu, *current_entry;
 
 %}
-%expect 30
+%expect 32
 
 %union
 {
@@ -62,6 +62,7 @@ static struct menu *current_menu, *current_entry;
 %token <id>T_TYPE
 %token <id>T_DEFAULT
 %token <id>T_SELECT
+%token <id>T_IMPLY
 %token <id>T_RANGE
 %token <id>T_VISIBLE
 %token <id>T_OPTION
@@ -124,7 +125,7 @@ stmt_list:
 ;
 
 option_name:
-       T_DEPENDS | T_PROMPT | T_TYPE | T_SELECT | T_OPTIONAL | T_RANGE | T_DEFAULT | T_VISIBLE
+       T_DEPENDS | T_PROMPT | T_TYPE | T_SELECT | T_IMPLY | T_OPTIONAL | T_RANGE | T_DEFAULT | T_VISIBLE
 ;
 
 common_stmt:
@@ -216,6 +217,12 @@ config_option: T_SELECT T_WORD if_expr T_EOL
        printd(DEBUG_PARSE, "%s:%d:select\n", zconf_curname(), zconf_lineno());
 };
 
+config_option: T_IMPLY T_WORD if_expr T_EOL
+{
+       menu_add_symbol(P_IMPLY, sym_lookup($2, 0), $3);
+       printd(DEBUG_PARSE, "%s:%d:imply\n", zconf_curname(), zconf_lineno());
+};
+
 config_option: T_RANGE symbol symbol if_expr T_EOL
 {
        menu_add_expr(P_RANGE, expr_alloc_comp(E_RANGE,$2, $3), $4);
@@ -664,6 +671,11 @@ static void print_symbol(FILE *out, struct menu *menu)
                        expr_fprint(prop->expr, out);
                        fputc('\n', out);
                        break;
+               case P_IMPLY:
+                       fputs( "  imply ", out);
+                       expr_fprint(prop->expr, out);
+                       fputc('\n', out);
+                       break;
                case P_RANGE:
                        fputs( "  range ", out);
                        expr_fprint(prop->expr, out);