Hi Markus,

On 1 February 2018 at 20:17, Marcus Folkesson
[off-list ref] wrote:

Hi Baolin,

On Tue, Jan 30, 2018 at 08:07:43PM +0800, Baolin Wang wrote:

quoted

The Spreadtrum SC9860 platform GPIO controller contains 16 groups and
each group contains 16 GPIOs. Each GPIO can set input/output and has
the interrupt capability.

Signed-off-by: Baolin Wang <redacted>
---

diff --git a/drivers/gpio/gpio-sprd.c b/drivers/gpio/gpio-sprd.c
new file mode 100644
index 0000000..af59b9f
--- /dev/null
+++ b/drivers/gpio/gpio-sprd.c

@@ -0,0 +1,301 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2018 Spreadtrum Communications Inc.
+ * Copyright (c) 2018 Linaro Ltd.
+ */
+
+#include <linux/bitops.h>
+#include <linux/gpio/driver.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/spinlock.h>
+
+/* GPIO registers definition */
+#define SPRD_GPIO_DATA               0x0
+#define SPRD_GPIO_DMSK               0x4
+#define SPRD_GPIO_DIR                0x8
+#define SPRD_GPIO_IS         0xc
+#define SPRD_GPIO_IBE                0x10
+#define SPRD_GPIO_IEV                0x14
+#define SPRD_GPIO_IE         0x18
+#define SPRD_GPIO_RIS                0x1c
+#define SPRD_GPIO_MIS                0x20
+#define SPRD_GPIO_IC         0x24
+#define SPRD_GPIO_INEN               0x28
+
+/* We have 16 groups GPIOs and each group contain 16 GPIOs */
+#define SPRD_GPIO_GROUP_NR   16
+#define SPRD_GPIO_NR         256
+#define SPRD_GPIO_GROUP_SIZE 0x80
+#define SPRD_GPIO_GROUP_MASK GENMASK(15, 0)
+#define SPRD_GPIO_BIT(x)     ((x) & (SPRD_GPIO_GROUP_NR - 1))
+
+struct sprd_gpio {
+     struct gpio_chip chip;
+     void __iomem *base;
+     spinlock_t lock;
+     int irq;
+};
+
+static inline void __iomem *sprd_gpio_group_base(struct sprd_gpio *sprd_gpio,
+                                              unsigned int group)
+{
+     return sprd_gpio->base + SPRD_GPIO_GROUP_SIZE * group;
+}
+
+static void sprd_gpio_update(struct gpio_chip *chip, unsigned int offset,
+                          unsigned int reg, unsigned int val)
+{
+     struct sprd_gpio *sprd_gpio = gpiochip_get_data(chip);
+     void __iomem *base = sprd_gpio_group_base(sprd_gpio,
+                                               offset / SPRD_GPIO_GROUP_NR);
+     u32 shift = SPRD_GPIO_BIT(offset);
+     unsigned long flags;
+     u32 orig, tmp;
+
+     spin_lock_irqsave(&sprd_gpio->lock, flags);
+     orig = readl_relaxed(base + reg);
+
+     tmp = (orig & ~BIT(shift)) | (val << shift);
+     writel_relaxed(tmp, base + reg);
+     spin_unlock_irqrestore(&sprd_gpio->lock, flags);
+}
+
+static int sprd_gpio_read(struct gpio_chip *chip, unsigned int offset,
+                       unsigned int reg)
+{
+     struct sprd_gpio *sprd_gpio = gpiochip_get_data(chip);
+     void __iomem *base = sprd_gpio_group_base(sprd_gpio,
+                                               offset / SPRD_GPIO_GROUP_NR);
+     u32 value = readl_relaxed(base + reg) & SPRD_GPIO_GROUP_MASK;
+     u32 shift = SPRD_GPIO_BIT(offset);
+
+     return !!(value & BIT(shift));
+}
+
+static int sprd_gpio_request(struct gpio_chip *chip, unsigned int offset)
+{
+     sprd_gpio_update(chip, offset, SPRD_GPIO_DMSK, 1);
+     return 0;
+}

Better to change the function to void since the return value is not
valueable.

The function prototype of gpio_chip structure need one return value,
so we need give one returned value though it is no meaningless.

quoted

+
+static void sprd_gpio_free(struct gpio_chip *chip, unsigned int offset)
+{
+     sprd_gpio_update(chip, offset, SPRD_GPIO_DMSK, 0);
+}
+
+static int sprd_gpio_direction_input(struct gpio_chip *chip,
+                                  unsigned int offset)
+{
+     sprd_gpio_update(chip, offset, SPRD_GPIO_DIR, 0);
+     sprd_gpio_update(chip, offset, SPRD_GPIO_INEN, 1);
+     return 0;
+}

Same here

quoted

+
+static int sprd_gpio_direction_output(struct gpio_chip *chip,
+                                   unsigned int offset, int value)
+{
+     sprd_gpio_update(chip, offset, SPRD_GPIO_DIR, 1);
+     sprd_gpio_update(chip, offset, SPRD_GPIO_INEN, 0);
+     sprd_gpio_update(chip, offset, SPRD_GPIO_DATA, value);
+     return 0;
+}

and here.


Thanks,
Marcus Folkesson

-- 
Baolin.wang
Best Regards