提交 ccdaeb2b 编写于 作者: A Alexander Aring 提交者: Marcel Holtmann

at86rf230: add support for external xtal trim

This patch adds support for setting the xtal trim register. Some at86rf2xx
transceiver boards needs fine tuning the xtal capacitor.
Signed-off-by: NAlexander Aring <alex.aring@gmail.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
上级 aaa1c4d2
......@@ -11,6 +11,8 @@ Required properties:
Optional properties:
- reset-gpio: GPIO spec for the rstn pin
- sleep-gpio: GPIO spec for the slp_tr pin
- xtal-trim: u8 value for fine tuning the internal capacitance
arrays of xtal pins: 0 = +0 pF, 0xf = +4.5 pF
Example:
......@@ -20,4 +22,5 @@ Example:
reg = <0>;
interrupts = <19 1>;
interrupt-parent = <&gpio3>;
xtal-trim = /bits/ 8 <0x06>;
};
......@@ -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;
......@@ -1378,9 +1417,11 @@ static int at86rf230_hw_init(struct at86rf230_local *lp)
}
static int
at86rf230_get_pdata(struct spi_device *spi, int *rstn, int *slp_tr)
at86rf230_get_pdata(struct spi_device *spi, int *rstn, int *slp_tr,
u8 *xtal_trim)
{
struct at86rf230_platform_data *pdata = spi->dev.platform_data;
int ret;
if (!IS_ENABLED(CONFIG_OF) || !spi->dev.of_node) {
if (!pdata)
......@@ -1388,11 +1429,15 @@ at86rf230_get_pdata(struct spi_device *spi, int *rstn, int *slp_tr)
*rstn = pdata->rstn;
*slp_tr = pdata->slp_tr;
*xtal_trim = pdata->xtal_trim;
return 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;
return 0;
}
......@@ -1505,13 +1550,14 @@ static int at86rf230_probe(struct spi_device *spi)
struct at86rf230_local *lp;
unsigned int status;
int rc, irq_type, rstn, slp_tr;
u8 xtal_trim;
if (!spi->irq) {
dev_err(&spi->dev, "no IRQ specified\n");
return -EINVAL;
}
rc = at86rf230_get_pdata(spi, &rstn, &slp_tr);
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;
......@@ -1570,7 +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;
......
......@@ -22,6 +22,7 @@ struct at86rf230_platform_data {
int rstn;
int slp_tr;
int dig2;
u8 xtal_trim;
};
#endif
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