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Date: Fri, 23 Feb 2018 11:58:27 -0400
From: Matheus Castello <matheus@...tello.eng.br>
To: Eric Anholt <eric@...olt.net>, stefan.wahren@...e.com
Cc: linus.walleij@...aro.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] pinctrl: bc2835: Add brcm,level property
Property to set initial value of pin output buffer.
This can be useful for configure hardware in overlay files, and in early boot
for checking it states in QA sanity tests.
This modification maintain the legacy property style, but the idea is to
continue working in this driver to implement support for the generic binding
properties too. So in the future this can be used to implement the
output-high and output-low generic properties.
Signed-off-by: Matheus Castello <matheus@...tello.eng.br>
---
.../bindings/pinctrl/brcm,bcm2835-gpio.txt | 5 +-
drivers/pinctrl/bcm/pinctrl-bcm2835.c | 90 +++++++++++++++++-----
2 files changed, 75 insertions(+), 20 deletions(-)
diff --git a/Documentation/devicetree/bindings/pinctrl/brcm,bcm2835-gpio.txt b/Documentation/devicetree/bindings/pinctrl/brcm,bcm2835-gpio.txt
index 2569866..6834f1d 100644
--- a/Documentation/devicetree/bindings/pinctrl/brcm,bcm2835-gpio.txt
+++ b/Documentation/devicetree/bindings/pinctrl/brcm,bcm2835-gpio.txt
@@ -54,8 +54,11 @@ Optional subnode-properties:
0: none
1: down
2: up
+- brcm,level: Integer, representing the value of output buffer to apply to the pin(s):
+ 0: low
+ 1: high
-Each of brcm,function and brcm,pull may contain either a single value which
+Each of brcm,function, brcm,pull and brcm,level may contain either a single value which
will be applied to all pins in brcm,pins, or 1 value for each entry in
brcm,pins.
diff --git a/drivers/pinctrl/bcm/pinctrl-bcm2835.c b/drivers/pinctrl/bcm/pinctrl-bcm2835.c
index 785c366..0ace548 100644
--- a/drivers/pinctrl/bcm/pinctrl-bcm2835.c
+++ b/drivers/pinctrl/bcm/pinctrl-bcm2835.c
@@ -73,6 +73,8 @@
enum bcm2835_pinconf_param {
/* argument: bcm2835_pinconf_pull */
BCM2835_PINCONF_PARAM_PULL,
+ /* argument: bcm2835_pinconf_level */
+ BCM2835_PINCONF_PARAM_LEVEL,
};
#define BCM2835_PINCONF_PACK(_param_, _arg_) ((_param_) << 16 | (_arg_))
@@ -725,16 +727,42 @@ static int bcm2835_pctl_dt_node_to_map_pull(struct bcm2835_pinctrl *pc,
return 0;
}
+static int bcm2835_pctl_dt_node_to_map_level(struct bcm2835_pinctrl *pc,
+ struct device_node *np, u32 pin, u32 level,
+ struct pinctrl_map **maps)
+{
+ struct pinctrl_map *map = *maps;
+ unsigned long *configs;
+
+ if (level > 2) {
+ dev_err(pc->dev, "%pOF: invalid brcm,level %d\n", np, level);
+ return -EINVAL;
+ }
+
+ configs = kzalloc(sizeof(*configs), GFP_KERNEL);
+ if (!configs)
+ return -ENOMEM;
+ configs[0] = BCM2835_PINCONF_PACK(BCM2835_PINCONF_PARAM_LEVEL, level);
+
+ map->type = PIN_MAP_TYPE_CONFIGS_PIN;
+ map->data.configs.group_or_pin = bcm2835_gpio_pins[pin].name;
+ map->data.configs.configs = configs;
+ map->data.configs.num_configs = 1;
+ (*maps)++;
+
+ return 0;
+}
+
static int bcm2835_pctl_dt_node_to_map(struct pinctrl_dev *pctldev,
struct device_node *np,
struct pinctrl_map **map, unsigned *num_maps)
{
struct bcm2835_pinctrl *pc = pinctrl_dev_get_drvdata(pctldev);
- struct property *pins, *funcs, *pulls;
- int num_pins, num_funcs, num_pulls, maps_per_pin;
+ struct property *pins, *funcs, *pulls, *levels;
+ int num_pins, num_funcs, num_pulls, num_levels, maps_per_pin;
struct pinctrl_map *maps, *cur_map;
int i, err;
- u32 pin, func, pull;
+ u32 pin, func, pull, level;
pins = of_find_property(np, "brcm,pins", NULL);
if (!pins) {
@@ -744,6 +772,7 @@ static int bcm2835_pctl_dt_node_to_map(struct pinctrl_dev *pctldev,
funcs = of_find_property(np, "brcm,function", NULL);
pulls = of_find_property(np, "brcm,pull", NULL);
+ levels = of_find_property(np, "brcm,level", NULL);
if (!funcs && !pulls) {
dev_err(pc->dev,
@@ -755,6 +784,7 @@ static int bcm2835_pctl_dt_node_to_map(struct pinctrl_dev *pctldev,
num_pins = pins->length / 4;
num_funcs = funcs ? (funcs->length / 4) : 0;
num_pulls = pulls ? (pulls->length / 4) : 0;
+ num_levels = levels ? (levels->length / 4) : 0;
if (num_funcs > 1 && num_funcs != num_pins) {
dev_err(pc->dev,
@@ -770,11 +800,20 @@ static int bcm2835_pctl_dt_node_to_map(struct pinctrl_dev *pctldev,
return -EINVAL;
}
+ if (num_levels > 1 && num_levels != num_pins) {
+ dev_err(pc->dev,
+ "%pOF: brcm,level must have 1 or %d entries\n",
+ np, num_pins);
+ return -EINVAL;
+ }
+
maps_per_pin = 0;
if (num_funcs)
maps_per_pin++;
if (num_pulls)
maps_per_pin++;
+ if (num_levels)
+ maps_per_pin++;
cur_map = maps = kzalloc(num_pins * maps_per_pin * sizeof(*maps),
GFP_KERNEL);
if (!maps)
@@ -811,6 +850,17 @@ static int bcm2835_pctl_dt_node_to_map(struct pinctrl_dev *pctldev,
if (err)
goto out;
}
+ if (num_levels) {
+ err = of_property_read_u32_index(np, "brcm,level",
+ (num_levels > 1) ? i : 0, &level);
+ if (err)
+ goto out;
+
+ err = bcm2835_pctl_dt_node_to_map_level(pc, np, pin,
+ level, &cur_map);
+ if (err)
+ goto out;
+ }
}
*map = maps;
@@ -931,23 +981,25 @@ static int bcm2835_pinconf_set(struct pinctrl_dev *pctldev,
param = BCM2835_PINCONF_UNPACK_PARAM(configs[i]);
arg = BCM2835_PINCONF_UNPACK_ARG(configs[i]);
- if (param != BCM2835_PINCONF_PARAM_PULL)
+ if (param == BCM2835_PINCONF_PARAM_PULL) {
+ off = GPIO_REG_OFFSET(pin);
+ bit = GPIO_REG_SHIFT(pin);
+
+ bcm2835_gpio_wr(pc, GPPUD, arg & 3);
+ /*
+ * Docs say to wait 150 cycles, but not of what. We assume a
+ * 1 MHz clock here, which is pretty slow...
+ */
+ udelay(150);
+ bcm2835_gpio_wr(pc, GPPUDCLK0 + (off * 4), BIT(bit));
+ udelay(150);
+ bcm2835_gpio_wr(pc, GPPUDCLK0 + (off * 4), 0);
+ } else if (param == BCM2835_PINCONF_PARAM_LEVEL) {
+ /* write in register */
+ bcm2835_gpio_set_bit(pc, arg ? GPSET0 : GPCLR0, pin);
+ } else {
return -EINVAL;
-
- off = GPIO_REG_OFFSET(pin);
- bit = GPIO_REG_SHIFT(pin);
-
- bcm2835_gpio_wr(pc, GPPUD, arg & 3);
- /*
- * BCM2835 datasheet say to wait 150 cycles, but not of what.
- * But the VideoCore firmware delay for this operation
- * based nearly on the same amount of VPU cycles and this clock
- * runs at 250 MHz.
- */
- udelay(1);
- bcm2835_gpio_wr(pc, GPPUDCLK0 + (off * 4), BIT(bit));
- udelay(1);
- bcm2835_gpio_wr(pc, GPPUDCLK0 + (off * 4), 0);
+ }
} /* for each config */
return 0;
--
2.7.4
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