media: dvb-frontends: add ST STV0910 DVB-S/S2 demodulator frontend driver

This adds a multi frontend driver for the ST STV0910 DVB-S/S2 demodulator
frontends. The driver code originates from the Digital Devices' dddvb
vendor driver package as of version 0.9.29, and has been cleaned up from
core API usage which isn't supported yet in the kernel, and additionally
all obvious style issues have been resolved. All camel case and allcaps
have been converted to kernel_case and lowercase. Patches have been sent
to the vendor package maintainers to fix this aswell. Signal statistics
acquisition has been refactored to comply with standards.

Permission to reuse and mainline the driver code was formally granted by
Ralph Metzler <rjkm@metzlerbros.de>.

Signed-off-by: Daniel Scheller <d.scheller@gmx.net>
Tested-by: Richard Scobie <r.scobie@clear.net.nz>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/media/dvb-frontends/Kconfig

@@ -28,6 +28,15 @@ config DVB_STV090x
 	  DVB-S/S2/DSS Multistandard Professional/Broadcast demodulators.
 	  Say Y when you want to support these frontends.
 
+config DVB_STV0910
+	tristate "STV0910 based"
+	depends on DVB_CORE && I2C
+	default m if !MEDIA_SUBDRV_AUTOSELECT
+	help
+	  ST STV0910 DVB-S/S2 demodulator driver.
+
+	  Say Y when you want to support these frontends.
+
 config DVB_STV6110x
 	tristate "STV6110/(A) based tuners"
 	depends on DVB_CORE && I2C

drivers/media/dvb-frontends/Makefile

@@ -110,6 +110,7 @@ obj-$(CONFIG_DVB_CXD2820R) += cxd2820r.o
 obj-$(CONFIG_DVB_CXD2841ER) += cxd2841er.o
 obj-$(CONFIG_DVB_DRXK) += drxk.o
 obj-$(CONFIG_DVB_TDA18271C2DD) += tda18271c2dd.o
+obj-$(CONFIG_DVB_STV0910) += stv0910.o
 obj-$(CONFIG_DVB_SI2165) += si2165.o
 obj-$(CONFIG_DVB_A8293) += a8293.o
 obj-$(CONFIG_DVB_SP2) += sp2.o

drivers/media/dvb-frontends/stv0910.h

@@ -0,0 +1,32 @@
+#ifndef _STV0910_H_
+#define _STV0910_H_
+
+#include <linux/types.h>
+#include <linux/i2c.h>
+
+struct stv0910_cfg {
+	u32 clk;
+	u8  adr;
+	u8  parallel;
+	u8  rptlvl;
+	u8  single;
+};
+
+#if IS_REACHABLE(CONFIG_DVB_STV0910)
+
+extern struct dvb_frontend *stv0910_attach(struct i2c_adapter *i2c,
+					   struct stv0910_cfg *cfg, int nr);
+
+#else
+
+static inline struct dvb_frontend *stv0910_attach(struct i2c_adapter *i2c,
+						  struct stv0910_cfg *cfg,
+						  int nr)
+{
+	pr_warn("%s: driver disabled by Kconfig\n", __func__);
+	return NULL;
+}
+
+#endif /* CONFIG_DVB_STV0910 */
+
+#endif /* _STV0910_H_ */