Subject: [PATCH 2/2] pinctrl: qcom: qdf2xxx: add support for new ACPI HID QCOM8002

From: [email-masked] (Timur Tabi)
Date: Fri, 23 Mar 2018 18:45:00 -0500

Newer versions of the firmware for the Qualcomm Datacenter Technologies
QDF2400 restricts access to a subset of the GPIOs on the TLMM.  To
prevent older kernels from accidentally accessing the restricted GPIOs,
we change the ACPI HID for the TLMM block from QCOM8001 to QCOM8002,
and introduce a new property "gpios".  This property is an array of
specific GPIOs that are accessible.  When an older kernel boots on
newer (restricted) firmware, it will fail to probe.

To implement the sparse GPIO map, we register all of the GPIOs, but
fill in the data only for available GPIOs.  This ensures that the driver
cannot accidentally access an unavailable GPIO.

The pinctrl-msm driver also scans the "gpios" property to determine
which pins are available, and ensure that only those can be registered.

Support for QCOM8001 is removed as there is no longer any firmware that
implements it.

Signed-off-by: Timur Tabi <[email-masked]>
---
 drivers/pinctrl/qcom/pinctrl-qdf2xxx.c | 114 +++++++++++++++++++++------------
 1 file changed, 73 insertions(+), 41 deletions(-)

diff --git a/drivers/pinctrl/qcom/pinctrl-qdf2xxx.c b/drivers/pinctrl/qcom/pinctrl-qdf2xxx.c
index bb3ce5c3e18b..1dfbe42dd895 100644
--- a/drivers/pinctrl/qcom/pinctrl-qdf2xxx.c
+++ b/drivers/pinctrl/qcom/pinctrl-qdf2xxx.c
@@ -30,9 +30,7 @@
 
 #include "pinctrl-msm.h"
 
-static struct msm_pinctrl_soc_data qdf2xxx_pinctrl;
-
-/* A reasonable limit to the number of GPIOS */
+/* A maximum of 256 allows us to use a u8 array to hold the GPIO numbers */
 #define MAX_GPIOS	256
 
 /* maximum size of each gpio name (enough room for "gpioXXX" + null) */
@@ -40,77 +38,111 @@
 
 static int qdf2xxx_pinctrl_probe(struct platform_device *pdev)
 {
+	struct msm_pinctrl_soc_data *pinctrl;
 	struct pinctrl_pin_desc *pins;
 	struct msm_pingroup *groups;
 	char (*names)[NAME_SIZE];
 	unsigned int i;
 	u32 num_gpios;
+	unsigned int avail_gpios; /* The number of GPIOs we support */
+	u8 gpios[MAX_GPIOS];      /* An array of supported GPIOs */
 	int ret;
 
 	/* Query the number of GPIOs from ACPI */
 	ret = device_property_read_u32(&pdev->dev, "num-gpios", &num_gpios);
 	if (ret < 0) {
-		dev_warn(&pdev->dev, "missing num-gpios property\n");
+		dev_err(&pdev->dev, "missing 'num-gpios' property\n");
 		return ret;
 	}
-
 	if (!num_gpios || num_gpios > MAX_GPIOS) {
-		dev_warn(&pdev->dev, "invalid num-gpios property\n");
+		dev_err(&pdev->dev, "invalid 'num-gpios' property\n");
+		return -ENODEV;
+	}
+
+	/* The number of GPIOs in the approved list */
+	ret = device_property_read_u8_array(&pdev->dev, "gpios", NULL, 0);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "missing 'gpios' property\n");
+		return ret;
+	}
+	/*
+	 * The number of available GPIOs should be non-zero, and no
+	 * more than the total number of GPIOS.
+	 */
+	if (!ret || ret > num_gpios) {
+		dev_err(&pdev->dev, "invalid 'gpios' property\n");
 		return -ENODEV;
 	}
+	avail_gpios = ret;
 
+	ret = device_property_read_u8_array(&pdev->dev, "gpios", gpios,
+					    avail_gpios);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "could not read list of GPIOs\n");
+		return ret;
+	}
+
+	pinctrl = devm_kzalloc(&pdev->dev, sizeof(*pinctrl), GFP_KERNEL);
 	pins = devm_kcalloc(&pdev->dev, num_gpios,
 		sizeof(struct pinctrl_pin_desc), GFP_KERNEL);
 	groups = devm_kcalloc(&pdev->dev, num_gpios,
 		sizeof(struct msm_pingroup), GFP_KERNEL);
-	names = devm_kcalloc(&pdev->dev, num_gpios, NAME_SIZE, GFP_KERNEL);
+	names = devm_kcalloc(&pdev->dev, avail_gpios, NAME_SIZE, GFP_KERNEL);
 
-	if (!pins || !groups || !names)
+	if (!pinctrl || !pins || !groups || !names)
 		return -ENOMEM;
 
+	/*
+	 * Initialize the array.  GPIOs not listed in the 'gpios' array
+	 * still need a number, but nothing else.
+	 */
 	for (i = 0; i < num_gpios; i++) {
-		snprintf(names[i], NAME_SIZE, "gpio%u", i);
-
 		pins[i].number = i;
-		pins[i].name = names[i];
-
-		groups[i].npins = 1;
-		groups[i].name = names[i];
 		groups[i].pins = &pins[i].number;
+	}
 
-		groups[i].ctl_reg = 0x10000 * i;
-		groups[i].io_reg = 0x04 + 0x10000 * i;
-		groups[i].intr_cfg_reg = 0x08 + 0x10000 * i;
-		groups[i].intr_status_reg = 0x0c + 0x10000 * i;
-		groups[i].intr_target_reg = 0x08 + 0x10000 * i;
-
-		groups[i].mux_bit = 2;
-		groups[i].pull_bit = 0;
-		groups[i].drv_bit = 6;
-		groups[i].oe_bit = 9;
-		groups[i].in_bit = 0;
-		groups[i].out_bit = 1;
-		groups[i].intr_enable_bit = 0;
-		groups[i].intr_status_bit = 0;
-		groups[i].intr_target_bit = 5;
-		groups[i].intr_target_kpss_val = 1;
-		groups[i].intr_raw_status_bit = 4;
-		groups[i].intr_polarity_bit = 1;
-		groups[i].intr_detection_bit = 2;
-		groups[i].intr_detection_width = 2;
+	/* Populate the entries that are meant to be exposed as GPIOs. */
+	for (i = 0; i < avail_gpios; i++) {
+		unsigned int gpio = gpios[i];
+
+		groups[gpio].npins = 1;
+		snprintf(names[i], NAME_SIZE, "gpio%u", gpio);
+		pins[gpio].name = names[i];
+		groups[gpio].name = names[i];
+
+		groups[gpio].ctl_reg = 0x10000 * gpio;
+		groups[gpio].io_reg = 0x04 + 0x10000 * gpio;
+		groups[gpio].intr_cfg_reg = 0x08 + 0x10000 * gpio;
+		groups[gpio].intr_status_reg = 0x0c + 0x10000 * gpio;
+		groups[gpio].intr_target_reg = 0x08 + 0x10000 * gpio;
+
+		groups[gpio].mux_bit = 2;
+		groups[gpio].pull_bit = 0;
+		groups[gpio].drv_bit = 6;
+		groups[gpio].oe_bit = 9;
+		groups[gpio].in_bit = 0;
+		groups[gpio].out_bit = 1;
+		groups[gpio].intr_enable_bit = 0;
+		groups[gpio].intr_status_bit = 0;
+		groups[gpio].intr_target_bit = 5;
+		groups[gpio].intr_target_kpss_val = 1;
+		groups[gpio].intr_raw_status_bit = 4;
+		groups[gpio].intr_polarity_bit = 1;
+		groups[gpio].intr_detection_bit = 2;
+		groups[gpio].intr_detection_width = 2;
 	}
 
-	qdf2xxx_pinctrl.pins = pins;
-	qdf2xxx_pinctrl.groups = groups;
-	qdf2xxx_pinctrl.npins = num_gpios;
-	qdf2xxx_pinctrl.ngroups = num_gpios;
-	qdf2xxx_pinctrl.ngpios = num_gpios;
+	pinctrl->pins = pins;
+	pinctrl->groups = groups;
+	pinctrl->npins = num_gpios;
+	pinctrl->ngroups = num_gpios;
+	pinctrl->ngpios = num_gpios;
 
-	return msm_pinctrl_probe(pdev, &qdf2xxx_pinctrl);
+	return msm_pinctrl_probe(pdev, pinctrl);
 }
 
 static const struct acpi_device_id qdf2xxx_acpi_ids[] = {
-	{"QCOM8001"},
+	{"QCOM8002"},
 	{},
 };
 MODULE_DEVICE_TABLE(acpi, qdf2xxx_acpi_ids);
-- 
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm
Technologies, Inc.  Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.