mmc: provide a standard MMC device-tree binding parser centrally

MMC defines a number of standard DT bindings. Having each driver parse
them individually adds code redundancy and is error prone. Provide a
standard function to unify the parsing. After all drivers are converted
to using it instead of their own parsers, this function can be integrated
into mmc_alloc_host().

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Chris Ball <cjb@laptop.org>

1 files changed, 110 insertions, 0 deletions

diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index ee2e16b17017..9c53452e73e1 100644
--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -15,6 +15,8 @@
 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/idr.h>
+#include <linux/of.h>
+#include <linux/of_gpio.h>
 #include <linux/pagemap.h>
 #include <linux/export.h>
 #include <linux/leds.h>
@@ -23,6 +25,7 @@
 
 #include <linux/mmc/host.h>
 #include <linux/mmc/card.h>
+#include <linux/mmc/slot-gpio.h>
 
 #include "core.h"
 #include "host.h"
@@ -295,6 +298,113 @@ static inline void mmc_host_clk_sysfs_init(struct mmc_host *host)
 #endif
 
 /**
+ *      mmc_of_parse() - parse host's device-tree node
+ *      @host: host whose node should be parsed.
+ *
+ * To keep the rest of the MMC subsystem unaware of whether DT has been
+ * used to to instantiate and configure this host instance or not, we
+ * parse the properties and set respective generic mmc-host flags and
+ * parameters.
+ */
+void mmc_of_parse(struct mmc_host *host)
+{
+        struct device_node *np;
+        u32 bus_width;
+        bool explicit_inv_wp, gpio_inv_wp = false;
+        enum of_gpio_flags flags;
+        int len, ret, gpio;
+
+        if (!host->parent || !host->parent->of_node)
+                return;
+
+        np = host->parent->of_node;
+
+        /* "bus-width" is translated to MMC_CAP_*_BIT_DATA flags */
+        if (of_property_read_u32(np, "bus-width", &bus_width) < 0) {
+                dev_dbg(host->parent,
+                        "\"bus-width\" property is missing, assuming 1 bit.\n");
+                bus_width = 1;
+        }
+
+        switch (bus_width) {
+        case 8:
+                host->caps |= MMC_CAP_8_BIT_DATA;
+                /* Hosts capable of 8-bit transfers can also do 4 bits */
+        case 4:
+                host->caps |= MMC_CAP_4_BIT_DATA;
+                break;
+        case 1:
+                break;
+        default:
+                dev_err(host->parent,
+                        "Invalid \"bus-width\" value %ud!\n", bus_width);
+        }
+
+        /* f_max is obtained from the optional "max-frequency" property */
+        of_property_read_u32(np, "max-frequency", &host->f_max);
+
+        /*
+         * Configure CD and WP pins. They are both by default active low to
+         * match the SDHCI spec. If GPIOs are provided for CD and / or WP, the
+         * mmc-gpio helpers are used to attach, configure and use them. If
+         * polarity inversion is specified in DT, one of MMC_CAP2_CD_ACTIVE_HIGH
+         * and MMC_CAP2_RO_ACTIVE_HIGH capability-2 flags is set. If the
+         * "broken-cd" property is provided, the MMC_CAP_NEEDS_POLL capability
+         * is set. If the "non-removable" property is found, the
+         * MMC_CAP_NONREMOVABLE capability is set and no card-detection
+         * configuration is performed.
+         */
+
+        /* Parse Card Detection */
+        if (of_find_property(np, "non-removable", &len)) {
+                host->caps |= MMC_CAP_NONREMOVABLE;
+        } else {
+                bool explicit_inv_cd, gpio_inv_cd = false;
+
+                explicit_inv_cd = of_property_read_bool(np, "cd-inverted");
+
+                if (of_find_property(np, "broken-cd", &len))
+                        host->caps |= MMC_CAP_NEEDS_POLL;
+
+                gpio = of_get_named_gpio_flags(np, "cd-gpios", 0, &flags);
+                if (gpio_is_valid(gpio)) {
+                        if (!(flags & OF_GPIO_ACTIVE_LOW))
+                                gpio_inv_cd = true;
+
+                        ret = mmc_gpio_request_cd(host, gpio);
+                        if (ret < 0)
+                                dev_err(host->parent,
+                                        "Failed to request CD GPIO #%d: %d!\n",
+                                        gpio, ret);
+                        else
+                                dev_info(host->parent, "Got CD GPIO #%d.\n",
+                                         gpio);
+                }
+
+                if (explicit_inv_cd ^ gpio_inv_cd)
+                        host->caps2 |= MMC_CAP2_CD_ACTIVE_HIGH;
+        }
+
+        /* Parse Write Protection */
+        explicit_inv_wp = of_property_read_bool(np, "wp-inverted");
+
+        gpio = of_get_named_gpio_flags(np, "wp-gpios", 0, &flags);
+        if (gpio_is_valid(gpio)) {
+                if (!(flags & OF_GPIO_ACTIVE_LOW))
+                        gpio_inv_wp = true;
+
+                ret = mmc_gpio_request_ro(host, gpio);
+                if (ret < 0)
+                        dev_err(host->parent,
+                                "Failed to request WP GPIO: %d!\n", ret);
+        }
+        if (explicit_inv_wp ^ gpio_inv_wp)
+                host->caps2 |= MMC_CAP2_RO_ACTIVE_HIGH;
+}
+
+EXPORT_SYMBOL(mmc_of_parse);
+
+/**
  *      mmc_alloc_host - initialise the per-host structure.
  *      @extra: sizeof private data structure
  *      @dev: pointer to host device model structure