gpio: stmpe: add verbose debug code

To troubleshoot the STMPE GPIO driver, some more detailed
debug information giving the exact info on how each pin is
used will be helpful.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

diff --git a/drivers/gpio/gpio-stmpe.c b/drivers/gpio/gpio-stmpe.c
index 866baa8..85c5b19 100644 (file)
--- a/drivers/gpio/gpio-stmpe.c
+++ b/drivers/gpio/gpio-stmpe.c
@@ -13,6 +13,7 @@
 #include <linux/interrupt.h>
 #include <linux/of.h>
 #include <linux/mfd/stmpe.h>
+#include <linux/seq_file.h>
 
 /*
  * These registers are modified under the irq bus lock and cached to avoid
@@ -211,6 +212,77 @@ static void stmpe_gpio_irq_unmask(struct irq_data *d)
        stmpe_gpio->regs[REG_IE][regoffset] |= mask;
 }
 
+static void stmpe_dbg_show_one(struct seq_file *s,
+                              struct gpio_chip *gc,
+                              unsigned offset, unsigned gpio)
+{
+       struct stmpe_gpio *stmpe_gpio = to_stmpe_gpio(gc);
+       struct stmpe *stmpe = stmpe_gpio->stmpe;
+       const char *label = gpiochip_is_requested(gc, offset);
+       int num_banks = DIV_ROUND_UP(stmpe->num_gpios, 8);
+       bool val = !!stmpe_gpio_get(gc, offset);
+       u8 dir_reg = stmpe->regs[STMPE_IDX_GPDR_LSB] - (offset / 8);
+       u8 mask = 1 << (offset % 8);
+       int ret;
+       u8 dir;
+
+       ret = stmpe_reg_read(stmpe, dir_reg);
+       if (ret < 0)
+               return;
+       dir = !!(ret & mask);
+
+       if (dir) {
+               seq_printf(s, " gpio-%-3d (%-20.20s) out %s",
+                          gpio, label ?: "(none)",
+                          val ? "hi" : "lo");
+       } else {
+               u8 edge_det_reg = stmpe->regs[STMPE_IDX_GPEDR_MSB] + num_banks - 1 - (offset / 8);
+               u8 rise_reg = stmpe->regs[STMPE_IDX_GPRER_LSB] - (offset / 8);
+               u8 fall_reg = stmpe->regs[STMPE_IDX_GPFER_LSB] - (offset / 8);
+               u8 irqen_reg = stmpe->regs[STMPE_IDX_IEGPIOR_LSB] - (offset / 8);
+               bool edge_det;
+               bool rise;
+               bool fall;
+               bool irqen;
+
+               ret = stmpe_reg_read(stmpe, edge_det_reg);
+               if (ret < 0)
+                       return;
+               edge_det = !!(ret & mask);
+               ret = stmpe_reg_read(stmpe, rise_reg);
+               if (ret < 0)
+                       return;
+               rise = !!(ret & mask);
+               ret = stmpe_reg_read(stmpe, fall_reg);
+               if (ret < 0)
+                       return;
+               fall = !!(ret & mask);
+               ret = stmpe_reg_read(stmpe, irqen_reg);
+               if (ret < 0)
+                       return;
+               irqen = !!(ret & mask);
+
+               seq_printf(s, " gpio-%-3d (%-20.20s) in  %s %s %s%s%s",
+                          gpio, label ?: "(none)",
+                          val ? "hi" : "lo",
+                          edge_det ? "edge-asserted" : "edge-inactive",
+                          irqen ? "IRQ-enabled" : "",
+                          rise ? " rising-edge-detection" : "",
+                          fall ? " falling-edge-detection" : "");
+       }
+}
+
+static void stmpe_dbg_show(struct seq_file *s, struct gpio_chip *gc)
+{
+       unsigned i;
+       unsigned gpio = gc->base;
+
+       for (i = 0; i < gc->ngpio; i++, gpio++) {
+               stmpe_dbg_show_one(s, gc, i, gpio);
+               seq_printf(s, "\n");
+       }
+}
+
 static struct irq_chip stmpe_gpio_irq_chip = {
        .name                   = "stmpe-gpio",
        .irq_bus_lock           = stmpe_gpio_irq_lock,
@@ -293,6 +365,9 @@ static int stmpe_gpio_probe(struct platform_device *pdev)
 #endif
        stmpe_gpio->chip.base = -1;
 
+       if (IS_ENABLED(CONFIG_DEBUG_FS))
+                stmpe_gpio->chip.dbg_show = stmpe_dbg_show;
+
        if (pdata)
                stmpe_gpio->norequest_mask = pdata->norequest_mask;
        else if (np)