[PATCH 2/2] pinctrl: qcom: Add qcom,remote-owned pin configuration support

[Pankaj Patil]

The eGPIO support added was incomplete since pin ownership is independent
of the selected mux function: the eGPIO present bit only describes
whether a pin is capable of being owned remotely, and the enable bit
selects the owner - 1 sets the owner as APPS and 0 sets the owner as
remote io. At present it's a mux level decision by setting the function
as "egpio", APPS releases the ownership to remote io and in process
cannot use it for any other function.

Add a driver specific pinconf parameter enabling the "qcom,remote-owned"
dt property support. pinconf-generic falls back to the default value of
1 whenever the property carries no value, and an absent property is
skipped entirely. Since pinconf-generic emits the mux mapping ahead of
the config mapping, this is applied after msm_pinmux_set_mux() has
set the pin ownership, giving the intended result for a state that
specifies both a function and remote-owned.

The hardware programming guide(hpg) explicitly mentions that the egpio
enable bit can be set independently of whatever the function select bits
are set to on targets which require shared ownership while the APPS
continues to use it as normal mux function.

msm_gpio_dbg_show_one() printed "egpio" and returned early whenever the
enable bit was clear, which was sufficient while that state could only be
reached by muxing to the egpio function. Ownership is no longer tied to
the mux, so report it as a suffix on the regular line and keep the
direction, value, mux, drive strength and bias visible. Pins muxed to the
egpio function reach the same register state and so print the full line
too; their mux field reflects the previously selected function.

Fixes: bebc49c1e5f6 ("pinctrl: qcom: Add egpio feature support")
Signed-off-by: Pankaj Patil <pankaj.patil@xxxxxxxxxxxxxxxx>
---
 drivers/pinctrl/qcom/pinctrl-msm.c | 81 ++++++++++++++++++++++++++++++++++----
 1 file changed, 73 insertions(+), 8 deletions(-)

diff --git a/drivers/pinctrl/qcom/pinctrl-msm.c b/drivers/pinctrl/qcom/pinctrl-msm.c
index 32aa7b919e24..4d96260f9909 100644
--- a/drivers/pinctrl/qcom/pinctrl-msm.c
+++ b/drivers/pinctrl/qcom/pinctrl-msm.c
@@ -48,6 +48,31 @@ struct msm_pin_state {
 	bool saved;
 };
 
+/*
+ * Driver specific pinconf parameter to hand a pin over to its eGPIO owner
+ * without muxing the TLMM away to the virtual eGPIO function. The eGPIO
+ * present bit only describes whether a pin is capable of being owned
+ * remotely; ownership itself is independent of the selected mux function,
+ * so a pin can keep its normal function selected while being owned by the
+ * remote subsystem.
+ *
+ * The "remote-owned" property is a boolean flag: its mere presence releases
+ * the pin to the remote owner. The default value below is what makes a
+ * valueless property come out as "release", as pinconf-generic falls back to
+ * it whenever the property carries no value.
+ */
+#define PIN_CONFIG_REMOTE_OWNED	(PIN_CONFIG_END + 1)
+
+static const struct pinconf_generic_params msm_gpio_bindings[] = {
+	{ "qcom,remote-owned", PIN_CONFIG_REMOTE_OWNED, 1 },
+};
+
+#ifdef CONFIG_DEBUG_FS
+static const struct pin_config_item msm_conf_items[] = {
+	PCONFDUMP(PIN_CONFIG_REMOTE_OWNED, "qcom,remote-owned", NULL, false),
+};
+#endif
+
 /**
  * struct msm_pinctrl - state for a pinctrl-msm device
  * @dev:            device handle.
@@ -328,6 +353,10 @@ static int msm_config_reg(struct msm_pinctrl *pctrl,
 		*bit = g->oe_bit;
 		*mask = 1;
 		break;
+	case PIN_CONFIG_REMOTE_OWNED:
+		*bit = g->egpio_enable;
+		*mask = 1;
+		break;
 	default:
 		return -ENOTSUPP;
 	}
@@ -424,6 +453,17 @@ static int msm_config_group_get(struct pinctrl_dev *pctldev,
 		if (!arg)
 			return -EINVAL;
 		break;
+	case PIN_CONFIG_REMOTE_OWNED:
+		/* Pin is not eGPIO capable */
+		if (!pctrl->soc->egpio_func || !(val & BIT(g->egpio_present)))
+			return -ENOTSUPP;
+
+		/* The enable bit is cleared when the remote owns the pin */
+		if (arg)
+			return -EINVAL;
+
+		arg = 1;
+		break;
 	default:
 		return -ENOTSUPP;
 	}
@@ -536,6 +576,29 @@ static int msm_config_group_set(struct pinctrl_dev *pctldev,
 		case PIN_CONFIG_OUTPUT_ENABLE:
 			arg = !!arg;
 			break;
+		case PIN_CONFIG_REMOTE_OWNED:
+			if (!pctrl->soc->egpio_func)
+				return -ENOTSUPP;
+
+			/*
+			 * Ownership may only be handed over on eGPIO capable
+			 * pins and is released by clearing the enable bit, so
+			 * this is applied here rather than through the generic
+			 * read-modify-write below.
+			 */
+			raw_spin_lock_irqsave(&pctrl->lock, flags);
+			val = msm_readl_ctl(pctrl, g);
+			if (!(val & BIT(g->egpio_present))) {
+				raw_spin_unlock_irqrestore(&pctrl->lock, flags);
+				dev_err(pctrl->dev, "%s is not eGPIO capable\n",
+					g->grp.name);
+				return -ENOTSUPP;
+			}
+
+			val &= ~BIT(g->egpio_enable);
+			msm_writel_ctl(val, pctrl, g);
+			raw_spin_unlock_irqrestore(&pctrl->lock, flags);
+			continue;
 		default:
 			dev_err(pctrl->dev, "Unsupported config parameter: %x\n",
 				param);
@@ -676,7 +739,7 @@ static void msm_gpio_dbg_show_one(struct seq_file *s,
 	int drive;
 	int pull;
 	int val;
-	int egpio_enable;
+	bool remote_owned;
 	u32 ctl_reg, io_reg;
 
 	static const char * const pulls_keeper[] = {
@@ -703,20 +766,15 @@ static void msm_gpio_dbg_show_one(struct seq_file *s,
 	func = (ctl_reg >> g->mux_bit) & 7;
 	drive = (ctl_reg >> g->drv_bit) & 7;
 	pull = (ctl_reg >> g->pull_bit) & 3;
-	egpio_enable = 0;
+	remote_owned = false;
 	if (pctrl->soc->egpio_func && ctl_reg & BIT(g->egpio_present))
-		egpio_enable = !(ctl_reg & BIT(g->egpio_enable));
+		remote_owned = !(ctl_reg & BIT(g->egpio_enable));
 
 	if (is_out)
 		val = !!(io_reg & BIT(g->out_bit));
 	else
 		val = !!(io_reg & BIT(g->in_bit));
 
-	if (egpio_enable) {
-		seq_printf(s, " %-8s: egpio\n", g->grp.name);
-		return;
-	}
-
 	seq_printf(s, " %-8s: %-3s", g->grp.name, is_out ? "out" : "in");
 	seq_printf(s, " %-4s func%d", str_high_low(val), func);
 	seq_printf(s, " %dmA", msm_regval_to_drive(drive));
@@ -724,6 +782,8 @@ static void msm_gpio_dbg_show_one(struct seq_file *s,
 		seq_printf(s, " %s", pulls_no_keeper[pull]);
 	else
 		seq_printf(s, " %s", pulls_keeper[pull]);
+	if (remote_owned)
+		seq_puts(s, " remote-owned");
 	seq_puts(s, "\n");
 }
 
@@ -1778,6 +1838,11 @@ int msm_pinctrl_probe(struct platform_device *pdev,
 	pctrl->desc.name = dev_name(&pdev->dev);
 	pctrl->desc.pins = pctrl->soc->pins;
 	pctrl->desc.npins = pctrl->soc->npins;
+	pctrl->desc.num_custom_params = ARRAY_SIZE(msm_gpio_bindings);
+	pctrl->desc.custom_params = msm_gpio_bindings;
+#ifdef CONFIG_DEBUG_FS
+	pctrl->desc.custom_conf_items = msm_conf_items;
+#endif
 
 	ret = devm_pinctrl_register_and_init(&pdev->dev, &pctrl->desc,
 					     pctrl, &pctrl->pctrl);

-- 
2.34.1