pinctrl: renesas: checker: Add reserved field checks

Add checks for discovering registers with reserved fields that could
benefit from being described using variable-width reserved field
shorthands, reducing kernel size.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/f5a5159ba7b396e6f09dd3f23c864a74ed8e342d.1649865241.git.geert+renesas@glider.be

diff --git a/drivers/pinctrl/renesas/core.c b/drivers/pinctrl/renesas/core.c
index ec88fe8..8c14b20 100644 (file)
--- a/drivers/pinctrl/renesas/core.c
+++ b/drivers/pinctrl/renesas/core.c
@@ -877,7 +877,7 @@ static const struct sh_pfc_pin __init *sh_pfc_find_pin(
 static void __init sh_pfc_check_cfg_reg(const char *drvname,
                                        const struct pinmux_cfg_reg *cfg_reg)
 {
-       unsigned int i, n, rw;
+       unsigned int i, n, rw, r;
        int fw;
 
        sh_pfc_check_reg(drvname, cfg_reg->reg,
@@ -886,6 +886,15 @@ static void __init sh_pfc_check_cfg_reg(const char *drvname,
        if (cfg_reg->field_width) {
                fw = cfg_reg->field_width;
                n = (cfg_reg->reg_width / fw) << fw;
+               for (i = 0, r = 0; i < n; i += 1 << fw) {
+                       if (is0s(&cfg_reg->enum_ids[i], 1 << fw))
+                               r++;
+               }
+
+               if ((r << fw) * sizeof(u16) > cfg_reg->reg_width / fw)
+                       sh_pfc_warn("reg 0x%x can be described with variable-width reserved fields\n",
+                                   cfg_reg->reg);
+
                /* Skip field checks (done at build time) */
                goto check_enum_ids;
        }