at86rf230: add support for external xtal trim

[deliverable/linux.git] / drivers / net / ieee802154 / at86rf230.c

diff --git a/drivers/net/ieee802154/at86rf230.c b/drivers/net/ieee802154/at86rf230.c
index 7b051eacb7f184a3770294b5b0d7d60aae5fbe2d..c1323e5cdd0ce826e89cdd86008ce018cf1d7f45 100644 (file)
--- a/drivers/net/ieee802154/at86rf230.c
+++ b/drivers/net/ieee802154/at86rf230.c
@@ -689,7 +689,7 @@ at86rf230_sync_state_change_complete(void *context)
 static int
 at86rf230_sync_state_change(struct at86rf230_local *lp, unsigned int state)
 {
-       int rc;
+       unsigned long rc;
 
        at86rf230_async_state_change(lp, &lp->state, state,
                                     at86rf230_sync_state_change_complete,
@@ -1315,7 +1315,7 @@ static struct at86rf2xx_chip_data at86rf212_data = {
        .get_desense_steps = at86rf212_get_desens_steps
 };
 
-static int at86rf230_hw_init(struct at86rf230_local *lp)
+static int at86rf230_hw_init(struct at86rf230_local *lp, u8 xtal_trim)
 {
        int rc, irq_type, irq_pol = IRQ_ACTIVE_HIGH;
        unsigned int dvdd;
@@ -1362,6 +1362,45 @@ static int at86rf230_hw_init(struct at86rf230_local *lp)
        usleep_range(lp->data->t_sleep_cycle,
                     lp->data->t_sleep_cycle + 100);
 
+       /* xtal_trim value is calculated by:
+        * CL = 0.5 * (CX + CTRIM + CPAR)
+        *
+        * whereas:
+        * CL = capacitor of used crystal
+        * CX = connected capacitors at xtal pins
+        * CPAR = in all at86rf2xx datasheets this is a constant value 3 pF,
+        *        but this is different on each board setup. You need to fine
+        *        tuning this value via CTRIM.
+        * CTRIM = variable capacitor setting. Resolution is 0.3 pF range is
+        *         0 pF upto 4.5 pF.
+        *
+        * Examples:
+        * atben transceiver:
+        *
+        * CL = 8 pF
+        * CX = 12 pF
+        * CPAR = 3 pF (We assume the magic constant from datasheet)
+        * CTRIM = 0.9 pF
+        *
+        * (12+0.9+3)/2 = 7.95 which is nearly at 8 pF
+        *
+        * xtal_trim = 0x3
+        *
+        * openlabs transceiver:
+        *
+        * CL = 16 pF
+        * CX = 22 pF
+        * CPAR = 3 pF (We assume the magic constant from datasheet)
+        * CTRIM = 4.5 pF
+        *
+        * (22+4.5+3)/2 = 14.75 which is the nearest value to 16 pF
+        *
+        * xtal_trim = 0xf
+        */
+       rc = at86rf230_write_subreg(lp, SR_XTAL_TRIM, xtal_trim);
+       if (rc)
+               return rc;
+
        rc = at86rf230_read_subreg(lp, SR_DVDD_OK, &dvdd);
        if (rc)
                return rc;
@@ -1377,24 +1416,30 @@ static int at86rf230_hw_init(struct at86rf230_local *lp)
        return at86rf230_write_subreg(lp, SR_SLOTTED_OPERATION, 0);
 }
 
-static struct at86rf230_platform_data *
-at86rf230_get_pdata(struct spi_device *spi)
+static int
+at86rf230_get_pdata(struct spi_device *spi, int *rstn, int *slp_tr,
+                   u8 *xtal_trim)
 {
-       struct at86rf230_platform_data *pdata;
+       struct at86rf230_platform_data *pdata = spi->dev.platform_data;
+       int ret;
 
-       if (!IS_ENABLED(CONFIG_OF) || !spi->dev.of_node)
-               return spi->dev.platform_data;
+       if (!IS_ENABLED(CONFIG_OF) || !spi->dev.of_node) {
+               if (!pdata)
+                       return -ENOENT;
 
-       pdata = devm_kzalloc(&spi->dev, sizeof(*pdata), GFP_KERNEL);
-       if (!pdata)
-               goto done;
+               *rstn = pdata->rstn;
+               *slp_tr = pdata->slp_tr;
+               *xtal_trim = pdata->xtal_trim;
+               return 0;
+       }
 
-       pdata->rstn = of_get_named_gpio(spi->dev.of_node, "reset-gpio", 0);
-       pdata->slp_tr = of_get_named_gpio(spi->dev.of_node, "sleep-gpio", 0);
+       *rstn = of_get_named_gpio(spi->dev.of_node, "reset-gpio", 0);
+       *slp_tr = of_get_named_gpio(spi->dev.of_node, "sleep-gpio", 0);
+       ret = of_property_read_u8(spi->dev.of_node, "xtal-trim", xtal_trim);
+       if (ret < 0 && ret != -EINVAL)
+               return ret;
 
-       spi->dev.platform_data = pdata;
-done:
-       return pdata;
+       return 0;
 }
 
 static int
@@ -1501,43 +1546,43 @@ at86rf230_setup_spi_messages(struct at86rf230_local *lp)
 
 static int at86rf230_probe(struct spi_device *spi)
 {
-       struct at86rf230_platform_data *pdata;
        struct ieee802154_hw *hw;
        struct at86rf230_local *lp;
        unsigned int status;
-       int rc, irq_type;
+       int rc, irq_type, rstn, slp_tr;
+       u8 xtal_trim;
 
        if (!spi->irq) {
                dev_err(&spi->dev, "no IRQ specified\n");
                return -EINVAL;
        }
 
-       pdata = at86rf230_get_pdata(spi);
-       if (!pdata) {
-               dev_err(&spi->dev, "no platform_data\n");
-               return -EINVAL;
+       rc = at86rf230_get_pdata(spi, &rstn, &slp_tr, &xtal_trim);
+       if (rc < 0) {
+               dev_err(&spi->dev, "failed to parse platform_data: %d\n", rc);
+               return rc;
        }
 
-       if (gpio_is_valid(pdata->rstn)) {
-               rc = devm_gpio_request_one(&spi->dev, pdata->rstn,
+       if (gpio_is_valid(rstn)) {
+               rc = devm_gpio_request_one(&spi->dev, rstn,
                                           GPIOF_OUT_INIT_HIGH, "rstn");
                if (rc)
                        return rc;
        }
 
-       if (gpio_is_valid(pdata->slp_tr)) {
-               rc = devm_gpio_request_one(&spi->dev, pdata->slp_tr,
+       if (gpio_is_valid(slp_tr)) {
+               rc = devm_gpio_request_one(&spi->dev, slp_tr,
                                           GPIOF_OUT_INIT_LOW, "slp_tr");
                if (rc)
                        return rc;
        }
 
        /* Reset */
-       if (gpio_is_valid(pdata->rstn)) {
+       if (gpio_is_valid(rstn)) {
                udelay(1);
-               gpio_set_value(pdata->rstn, 0);
+               gpio_set_value(rstn, 0);
                udelay(1);
-               gpio_set_value(pdata->rstn, 1);
+               gpio_set_value(rstn, 1);
                usleep_range(120, 240);
        }
 
@@ -1571,7 +1616,7 @@ static int at86rf230_probe(struct spi_device *spi)
 
        spi_set_drvdata(spi, lp);
 
-       rc = at86rf230_hw_init(lp);
+       rc = at86rf230_hw_init(lp, xtal_trim);
        if (rc)
                goto free_dev;