[DRIVERS] Porting: Add SECO GSM modem power management

Driver provides support for reset, power enable lines,
that are controlled by GPIOs.

Driver added to the miscellaneous drivers source tree.

Thid driver is needed to initialize the LTE Cat 4 modem module QUECTEL EG25-G.

drivers/misc/Kconfig

@@ -487,6 +487,10 @@ config HISI_HIKEY_USB
 	  switching between the dual-role USB-C port and the USB-A host ports
 	  using only one USB controller.
 
+config SECO_GSM_POWER_MANAGER
+	tristate "SECO GSM modem power management"
+	depends on GPIOLIB && OF
+
 source "drivers/misc/c2port/Kconfig"
 source "drivers/misc/eeprom/Kconfig"
 source "drivers/misc/cb710/Kconfig"

drivers/misc/Makefile

@@ -59,3 +59,4 @@ obj-$(CONFIG_UACCE)		+= uacce/
 obj-$(CONFIG_XILINX_SDFEC)	+= xilinx_sdfec.o
 obj-$(CONFIG_HISI_HIKEY_USB)	+= hisi_hikey_usb.o
 obj-$(CONFIG_UID_SYS_STATS)	+= uid_sys_stats.o
+obj-$(CONFIG_SECO_GSM_POWER_MANAGER) += gsm-modem.o

drivers/misc/gsm-modem.c

+/*
+ * GSM MODEM initialization driver
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/gpio.h>
+#include <linux/of_gpio.h>
+#include <linux/io.h>
+#include <linux/delay.h>
+#include <asm/uaccess.h>
+#include <linux/ioctl.h>
+#include <linux/major.h>
+#include <linux/cdev.h>
+#include <linux/sched.h>
+#include <linux/device.h>
+#include <linux/timer.h>
+#include <linux/platform_device.h>
+
+#include <linux/init.h>
+#include <linux/smp.h>
+#include <asm/cacheflush.h>
+#include <asm/page.h>
+
+static int usben_gpio, rst_gpio, pwrkey_gpio, vgsm_gpio;
+
+int gsm_modem_config_of(struct device_node *node) {
+
+	int retval;
+
+	/* request reset pin */
+        rst_gpio = of_get_named_gpio(node, "rst-gpios", 0);
+        if (!gpio_is_valid(rst_gpio)) {
+                pr_err("gsm-modem: no modem reset pin available gpios = %d\n",rst_gpio);
+                return -EINVAL;
+        }
+        retval = gpio_request(rst_gpio, "gsm-modem_reset");
+        if (retval < 0)
+                return retval;
+
+	/* request pwrkey pin */
+        pwrkey_gpio = of_get_named_gpio(node, "pwrkey-gpios", 0);
+        if (!gpio_is_valid(pwrkey_gpio)) {
+                pr_err("gsm-modem: no modem pwrkey pin available\n");
+                return -EINVAL;
+        }
+        retval = gpio_request(pwrkey_gpio, "gsm-modem_pwrkey");
+        if (retval < 0)
+                return retval;
+
+	/* request usben pin */
+        usben_gpio = of_get_named_gpio(node, "usben-gpios", 0);
+        if (!gpio_is_valid(usben_gpio)) {
+                pr_err("gsm-modem: no modem usb enable pin available\n");
+                return -EINVAL;
+        }
+        retval = gpio_request(usben_gpio, "gsm-modem_usben");
+        if (retval < 0)
+                return retval;
+
+	/* request vgsm pin */
+        vgsm_gpio = of_get_named_gpio(node, "vgsm-gpios", 0);
+        if (!gpio_is_valid(vgsm_gpio)) {
+                pr_err("gsm-modem: no modem vgsm enable pin available\n");
+                return -EINVAL;
+        }
+        retval = gpio_request(vgsm_gpio, "gsm-modem_vgsm");
+        if (retval < 0)
+                return retval;
+
+        return 0;
+}
+
+int gsm_modem_probe (struct platform_device *pdev)
+{
+
+	struct device_node *np = pdev->dev.of_node;
+
+        pr_info ("gsm modem probing...\n");
+
+	if(!np)	{
+		pr_err("gsm-modem: no dts config found - probe failed\n");
+		return -ENODEV;
+	}
+
+        /* DTS init */
+	if(gsm_modem_config_of(np) < 0) {
+	       pr_err("gsm-modem: no gsm-modem dts config found - probe failed\n");
+	       return -ENODEV;
+	}
+
+	/* Initializing modem */
+	gpio_direction_output(usben_gpio,0);
+	gpio_direction_output(vgsm_gpio,0);
+	gpio_direction_output(pwrkey_gpio,0);
+	gpio_direction_output(rst_gpio,1);
+	udelay(100);
+	gpio_direction_output(vgsm_gpio,1);
+	udelay(10);
+	gpio_direction_output(rst_gpio,0);
+	udelay(10);
+	gpio_direction_output(pwrkey_gpio,1);
+	mdelay(2*500);
+	gpio_direction_output(pwrkey_gpio,0);
+
+	pr_info ("gsm-modem: done\n");
+
+	return 0;
+}
+
+static int gsm_modem_remove(struct platform_device *pdev)
+{
+	gpio_free(vgsm_gpio);
+	gpio_free(usben_gpio);
+	gpio_free(pwrkey_gpio);
+	gpio_free(rst_gpio);
+
+        return 0;
+}
+
+static void gsm_modem_shutdown(struct platform_device *pdev)
+{
+	gpio_free(vgsm_gpio);
+        gpio_free(usben_gpio);
+        gpio_free(pwrkey_gpio);
+        gpio_free(rst_gpio);
+
+        pr_info("gsm-modem exit\n");
+}
+
+static const struct of_device_id gsm_modem_dt_ids[] = {
+        { .compatible = "seco,gsm-modem", },
+        { /*sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, gsm_modem_dt_ids);
+
+static struct platform_driver gsm_modem_driver = {
+        .probe          = gsm_modem_probe,
+        .remove         = gsm_modem_remove,
+        .shutdown       = gsm_modem_shutdown,
+        .driver         = {
+                .name   = "gsm-modem",
+                .of_match_table = gsm_modem_dt_ids,
+        },
+};
+
+module_platform_driver(gsm_modem_driver);
+
+MODULE_ALIAS("platform:gsm_modem");
+MODULE_AUTHOR("MS SECO, Inc.");
+MODULE_DESCRIPTION("GSM Modem Initialization Driver");
+MODULE_LICENSE("GPL");