V4L/DVB (9364): adding sharp s921 ISDB-T driver

s921_module.c:
    wrapper for the dvb frontend interface
    s921_core.c:
    core s921 1seg ISDB-T driver, everything is set to auto as much as possible
    in order to not require certain parameters which currently cannot be passed
    to the ISDB-T chip.

    ISDB-T support can be tested using dvbscan, dvbstream/snoop and mplayer
    Tested 1seg H264/aac stream with this driver using a custom linux
ISDB-T player
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/empia/sharp/Makefile

+s921-objs := s921_module.o s921_core.o
+
+obj-m += s921.o

drivers/media/video/empia/sharp/s921_core.c

+/*
+ * Driver for Sharp s921 driver
+ *
+ * Copyright (C) 2008 Markus Rechberger <mrechberger@sundtek.de>
+ *
+ */
+
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include "s921_core.h"
+
+static int s921_isdb_init(struct s921_isdb_t *dev);
+static int s921_isdb_set_parameters(struct s921_isdb_t *dev, struct s921_isdb_t_transmission_mode_params *params);
+static int s921_isdb_tune(struct s921_isdb_t *dev, struct s921_isdb_t_tune_params *params);
+static int s921_isdb_get_status(struct s921_isdb_t *dev, void *data);
+
+static u8 init_table[]={ 0x01, 0x40, 0x02, 0x00, 0x03, 0x40, 0x04, 0x01,
+                         0x05, 0x00, 0x06, 0x00, 0x07, 0x00, 0x08, 0x00,
+                         0x09, 0x00, 0x0a, 0x00, 0x0b, 0x5a, 0x0c, 0x00,
+                         0x0d, 0x00, 0x0f, 0x00, 0x13, 0x1b, 0x14, 0x80,
+                         0x15, 0x40, 0x17, 0x70, 0x18, 0x01, 0x19, 0x12,
+                         0x1a, 0x01, 0x1b, 0x12, 0x1c, 0xa0, 0x1d, 0x00,
+                         0x1e, 0x0a, 0x1f, 0x08, 0x20, 0x40, 0x21, 0xff,
+                         0x22, 0x4c, 0x23, 0x4e, 0x24, 0x4c, 0x25, 0x00,
+                         0x26, 0x00, 0x27, 0xf4, 0x28, 0x60, 0x29, 0x88,
+                         0x2a, 0x40, 0x2b, 0x40, 0x2c, 0xff, 0x2d, 0x00,
+                         0x2e, 0xff, 0x2f, 0x00, 0x30, 0x20, 0x31, 0x06,
+                         0x32, 0x0c, 0x34, 0x0f, 0x37, 0xfe, 0x38, 0x00,
+                         0x39, 0x63, 0x3a, 0x10, 0x3b, 0x10, 0x47, 0x00,
+                         0x49, 0xe5, 0x4b, 0x00, 0x50, 0xc0, 0x52, 0x20,
+                         0x54, 0x5a, 0x55, 0x5b, 0x56, 0x40, 0x57, 0x70,
+                         0x5c, 0x50, 0x5d, 0x00, 0x62, 0x17, 0x63, 0x2f,
+                         0x64, 0x6f, 0x68, 0x00, 0x69, 0x89, 0x6a, 0x00,
+                         0x6b, 0x00, 0x6c, 0x00, 0x6d, 0x00, 0x6e, 0x00,
+                         0x70, 0x00, 0x71, 0x00, 0x75, 0x00, 0x76, 0x30,
+                         0x77, 0x01, 0xaf, 0x00, 0xb0, 0xa0, 0xb2, 0x3d,
+                         0xb3, 0x25, 0xb4, 0x8b, 0xb5, 0x4b, 0xb6, 0x3f,
+                         0xb7, 0xff, 0xb8, 0xff, 0xb9, 0xfc, 0xba, 0x00,
+                         0xbb, 0x00, 0xbc, 0x00, 0xd0, 0x30, 0xe4, 0x84,
+                         0xf0, 0x48, 0xf1, 0x19, 0xf2, 0x5a, 0xf3, 0x8e,
+                         0xf4, 0x2d, 0xf5, 0x07, 0xf6, 0x5a, 0xf7, 0xba,
+                         0xf8, 0xd7 };
+
+static u8 c_table[]={ 0x58, 0x8a, 0x7b, 0x59, 0x8c, 0x7b, 0x5a, 0x8e, 0x5b,
+                      0x5b, 0x90, 0x5b, 0x5c, 0x92, 0x5b, 0x5d, 0x94, 0x5b,
+                      0x5e, 0x96, 0x5b, 0x5f, 0x98, 0x3b, 0x60, 0x9a, 0x3b,
+                      0x61, 0x9c, 0x3b, 0x62, 0x9e, 0x3b, 0x63, 0xa0, 0x3b,
+                      0x64, 0xa2, 0x1b, 0x65, 0xa4, 0x1b, 0x66, 0xa6, 0x1b,
+                      0x67, 0xa8, 0x1b, 0x68, 0xaa, 0x1b, 0x69, 0xac, 0x1b,
+                      0x6a, 0xae, 0x1b, 0x6b, 0xb0, 0x1b, 0x6c, 0xb2, 0x1b,
+                      0x6d, 0xb4, 0xfb, 0x6e, 0xb6, 0xfb, 0x6f, 0xb8, 0xfb,
+                      0x70, 0xba, 0xfb, 0x71, 0xbc, 0xdb, 0x72, 0xbe, 0xdb,
+                      0x73, 0xc0, 0xdb, 0x74, 0xc2, 0xdb, 0x75, 0xc4, 0xdb,
+                      0x76, 0xc6, 0xdb, 0x77, 0xc8, 0xbb, 0x78, 0xca, 0xbb,
+                      0x79, 0xcc, 0xbb, 0x7a, 0xce, 0xbb, 0x7b, 0xd0, 0xbb,
+                      0x7c, 0xd2, 0xbb, 0x7d, 0xd4, 0xbb, 0x7e, 0xd6, 0xbb,
+                      0x7f, 0xd8, 0xbb, 0x80, 0xda, 0x9b, 0x81, 0xdc, 0x9b,
+                      0x82, 0xde, 0x9b, 0x83, 0xe0, 0x9b, 0x84, 0xe2, 0x9b,
+                      0x85, 0xe4, 0x9b, 0x86, 0xe6, 0x9b, 0x87, 0xe8, 0x9b,
+                      0x88, 0xea, 0x9b, 0x89, 0xec, 0x9b };
+
+int s921_isdb_cmd(struct s921_isdb_t *dev, u32 cmd, void *data) {
+	switch(cmd) {
+	case ISDB_T_CMD_INIT:
+		s921_isdb_init(dev);
+		break;
+	case ISDB_T_CMD_SET_PARAM:
+		s921_isdb_set_parameters(dev, data);
+		break;
+	case ISDB_T_CMD_TUNE:
+		s921_isdb_tune(dev, data);
+		break;
+	case ISDB_T_CMD_GET_STATUS:
+		s921_isdb_get_status(dev, data);
+		break;
+	default:
+		printk("unhandled command\n");
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static int s921_isdb_init(struct s921_isdb_t *dev) {
+	unsigned int i;
+	unsigned int ret;
+        printk("isdb_init\n");
+	for (i = 0; i < sizeof(init_table); i+=2) {
+		ret = dev->i2c_write(dev->priv_dev, init_table[i], init_table[i+1]);
+		if (ret != 0) {
+			printk("i2c write failed\n");
+			return ret;
+		}
+	}
+	return 0;
+}
+
+static int s921_isdb_set_parameters(struct s921_isdb_t *dev, struct s921_isdb_t_transmission_mode_params *params) {
+
+	int ret;
+	/* auto is sufficient for now, lateron this should be reflected in an extra interface */
+
+
+
+	ret = dev->i2c_write(dev->priv_dev, 0xb0, 0xa0); //mod_b2);
+	ret = dev->i2c_write(dev->priv_dev, 0xb2, 0x3d); //mod_b2);
+
+	if (ret < 0)
+		return -EINVAL;
+
+	ret = dev->i2c_write(dev->priv_dev, 0xb3, 0x25); //mod_b3);
+	if (ret < 0)
+		return -EINVAL;
+
+	ret = dev->i2c_write(dev->priv_dev, 0xb4, 0x8b); //mod_b4);
+	if (ret < 0)
+		return -EINVAL;
+
+	ret = dev->i2c_write(dev->priv_dev, 0xb5, 0x4b); //mod_b5);
+	if (ret < 0)
+		return -EINVAL;
+
+	ret = dev->i2c_write(dev->priv_dev, 0xb6, 0x3f); //mod_b6);
+	if (ret < 0)
+		return -EINVAL;
+
+	ret = dev->i2c_write(dev->priv_dev, 0xb7, 0x3f); //mod_b7);
+	if (ret < 0)
+		return -EINVAL;
+
+	return E_OK;
+}
+
+static int s921_isdb_tune(struct s921_isdb_t *dev, struct s921_isdb_t_tune_params *params) {
+
+	int ret;
+	int index;
+
+	index = (params->frequency - 473143000)/6000000;
+
+	if (index > 48) {
+		return -EINVAL;
+	}
+
+	dev->i2c_write(dev->priv_dev, 0x47, 0x60);
+
+	ret = dev->i2c_write(dev->priv_dev, 0x68, 0x00);
+	if (ret < 0)
+		return -EINVAL;
+
+	ret = dev->i2c_write(dev->priv_dev, 0x69, 0x89);
+	if (ret < 0)
+		return -EINVAL;
+
+	ret = dev->i2c_write(dev->priv_dev, 0xf0, 0x48);
+	if (ret < 0)
+		return -EINVAL;
+
+	ret = dev->i2c_write(dev->priv_dev, 0xf1, 0x19);
+	if (ret < 0)
+		return -EINVAL;
+
+	ret = dev->i2c_write(dev->priv_dev, 0xf2, c_table[index*3]);
+	if (ret < 0)
+		return -EINVAL;
+
+	ret = dev->i2c_write(dev->priv_dev, 0xf3, c_table[index*3+1]);
+	if (ret < 0)
+		return -EINVAL;
+
+	ret = dev->i2c_write(dev->priv_dev, 0xf4, c_table[index*3+2]);
+	if (ret < 0)
+		return -EINVAL;
+
+	ret = dev->i2c_write(dev->priv_dev, 0xf5, 0xae);
+	if (ret < 0)
+		return -EINVAL;
+
+	ret = dev->i2c_write(dev->priv_dev, 0xf6, 0xb7);
+	if (ret < 0)
+		return -EINVAL;
+
+	ret = dev->i2c_write(dev->priv_dev, 0xf7, 0xba);
+	if (ret < 0)
+		return -EINVAL;
+
+	ret = dev->i2c_write(dev->priv_dev, 0xf8, 0xd7);
+	if (ret < 0)
+		return -EINVAL;
+
+	ret = dev->i2c_write(dev->priv_dev, 0x68, 0x0a);
+	if (ret < 0)
+		return -EINVAL;
+
+	ret = dev->i2c_write(dev->priv_dev, 0x69, 0x09);
+	if (ret < 0)
+		return -EINVAL;
+
+	dev->i2c_write(dev->priv_dev, 0x01, 0x40);
+	return 0;
+}
+
+static int s921_isdb_get_status(struct s921_isdb_t *dev, void *data) {
+	unsigned int *ret = (unsigned int*)data;
+	u8 ifagc_dt;
+	u8 rfagc_dt;
+
+	mdelay(10);
+	ifagc_dt = dev->i2c_read(dev->priv_dev, 0x81);
+	rfagc_dt = dev->i2c_read(dev->priv_dev, 0x82);
+	if (rfagc_dt == 0x40) {
+		*ret = 1;
+	}
+	return 0;
+}

drivers/media/video/empia/sharp/s921_core.h

+#ifndef _S921_CORE_H
+#define _S921_CORE_H
+//#define u8 unsigned int
+//#define u32 unsigned int
+
+
+
+//#define EINVAL -1
+#define E_OK 0
+
+struct s921_isdb_t {
+	void *priv_dev;
+	int (*i2c_write)(void *dev, u8 reg, u8 val);
+	int (*i2c_read)(void *dev, u8 reg);
+};
+
+#define ISDB_T_CMD_INIT       0
+#define ISDB_T_CMD_SET_PARAM  1
+#define ISDB_T_CMD_TUNE       2
+#define ISDB_T_CMD_GET_STATUS 3
+
+struct s921_isdb_t_tune_params {
+	u32 frequency;
+};
+
+struct s921_isdb_t_status {
+};
+
+struct s921_isdb_t_transmission_mode_params {
+	u8 mode;
+	u8 layer_a_mode;
+#define ISDB_T_LA_MODE_1 0
+#define ISDB_T_LA_MODE_2 1
+#define ISDB_T_LA_MODE_3 2
+	u8 layer_a_carrier_modulation;
+#define ISDB_T_LA_CM_DQPSK 0
+#define ISDB_T_LA_CM_QPSK  1
+#define ISDB_T_LA_CM_16QAM 2
+#define ISDB_T_LA_CM_64QAM 3
+#define ISDB_T_LA_CM_NOLAYER 4
+	u8 layer_a_code_rate;
+#define ISDB_T_LA_CR_1_2   0
+#define ISDB_T_LA_CR_2_3   1
+#define ISDB_T_LA_CR_3_4   2
+#define ISDB_T_LA_CR_5_6   4
+#define ISDB_T_LA_CR_7_8   8
+#define ISDB_T_LA_CR_NOLAYER   16
+	u8 layer_a_time_interleave;
+#define ISDB_T_LA_TI_0  0
+#define ISDB_T_LA_TI_1  1
+#define ISDB_T_LA_TI_2  2
+#define ISDB_T_LA_TI_4  4
+#define ISDB_T_LA_TI_8  8
+#define ISDB_T_LA_TI_16 16
+#define ISDB_T_LA_TI_32 32
+	u8 layer_a_nseg;
+
+	u8 layer_b_mode;
+#define ISDB_T_LB_MODE_1 0
+#define ISDB_T_LB_MODE_2 1
+#define ISDB_T_LB_MODE_3 2
+	u8 layer_b_carrier_modulation;
+#define ISDB_T_LB_CM_DQPSK 0
+#define ISDB_T_LB_CM_QPSK  1
+#define ISDB_T_LB_CM_16QAM 2
+#define ISDB_T_LB_CM_64QAM 3
+#define ISDB_T_LB_CM_NOLAYER 4
+	u8 layer_b_code_rate;
+#define ISDB_T_LB_CR_1_2   0
+#define ISDB_T_LB_CR_2_3   1
+#define ISDB_T_LB_CR_3_4   2
+#define ISDB_T_LB_CR_5_6   4
+#define ISDB_T_LB_CR_7_8   8
+#define ISDB_T_LB_CR_NOLAYER   16
+	u8 layer_b_time_interleave;
+#define ISDB_T_LB_TI_0  0
+#define ISDB_T_LB_TI_1  1
+#define ISDB_T_LB_TI_2  2
+#define ISDB_T_LB_TI_4  4
+#define ISDB_T_LB_TI_8  8
+#define ISDB_T_LB_TI_16 16
+#define ISDB_T_LB_TI_32 32
+	u8 layer_b_nseg;
+
+	u8 layer_c_mode;
+#define ISDB_T_LC_MODE_1 0
+#define ISDB_T_LC_MODE_2 1
+#define ISDB_T_LC_MODE_3 2
+	u8 layer_c_carrier_modulation;
+#define ISDB_T_LC_CM_DQPSK 0
+#define ISDB_T_LC_CM_QPSK  1
+#define ISDB_T_LC_CM_16QAM 2
+#define ISDB_T_LC_CM_64QAM 3
+#define ISDB_T_LC_CM_NOLAYER 4
+	u8 layer_c_code_rate;
+#define ISDB_T_LC_CR_1_2   0
+#define ISDB_T_LC_CR_2_3   1
+#define ISDB_T_LC_CR_3_4   2
+#define ISDB_T_LC_CR_5_6   4
+#define ISDB_T_LC_CR_7_8   8
+#define ISDB_T_LC_CR_NOLAYER   16
+	u8 layer_c_time_interleave;
+#define ISDB_T_LC_TI_0  0
+#define ISDB_T_LC_TI_1  1
+#define ISDB_T_LC_TI_2  2
+#define ISDB_T_LC_TI_4  4
+#define ISDB_T_LC_TI_8  8
+#define ISDB_T_LC_TI_16 16
+#define ISDB_T_LC_TI_32 32
+	u8 layer_c_nseg;
+};
+
+int s921_isdb_cmd(struct s921_isdb_t *dev, u32 cmd, void *data);
+#endif

drivers/media/video/empia/sharp/s921_module.c

+/*
+ * Driver for Sharp s921 driver
+ *
+ * Copyright (C) 2008 Markus Rechberger <mrechberger@sundtek.de>
+ *
+ * All rights reserved.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/delay.h>
+#include "dvb_frontend.h"
+#include "s921_module.h"
+#include "s921_core.h"
+
+static  unsigned int debug = 0;
+module_param(debug, int, 0644);
+MODULE_PARM_DESC(debug,"s921 debugging (default off)");
+
+#define dprintk(fmt, args...) if (debug) do {\
+			printk("s921 debug: " fmt, ##args); } while (0)
+
+struct s921_state
+{
+        struct dvb_frontend frontend;
+        fe_modulation_t current_modulation;
+        __u32 snr;
+        __u32 current_frequency;
+	__u8 addr;
+	struct s921_isdb_t dev;
+	struct i2c_adapter *i2c;
+};
+
+static int s921_set_parameters(struct dvb_frontend *fe, struct dvb_frontend_parameters *param) {
+	struct s921_state *state = (struct s921_state *)fe->demodulator_priv;
+	struct s921_isdb_t_transmission_mode_params params;
+	struct s921_isdb_t_tune_params tune_params;
+
+	tune_params.frequency = param->frequency;
+	s921_isdb_cmd(&state->dev, ISDB_T_CMD_SET_PARAM, &params);
+	s921_isdb_cmd(&state->dev, ISDB_T_CMD_TUNE, &tune_params);
+	mdelay(100);
+	return 0;
+}
+
+static int s921_init(struct dvb_frontend *fe) {
+	printk("s921 init\n");
+        return 0;
+}
+
+static int s921_sleep(struct dvb_frontend *fe) {
+	printk("s921 sleep\n");
+	return 0;
+}
+
+static int s921_read_status(struct dvb_frontend *fe, fe_status_t *status)
+{
+	struct s921_state *state = (struct s921_state *)fe->demodulator_priv;
+	unsigned int ret;
+	mdelay(5);
+	s921_isdb_cmd(&state->dev, ISDB_T_CMD_GET_STATUS, &ret);
+	*status = 0;
+
+	printk("status: %02x\n", ret);
+	if (ret == 1) {
+		*status |= FE_HAS_CARRIER;
+		*status |= FE_HAS_VITERBI;
+		*status |= FE_HAS_LOCK;
+		*status |= FE_HAS_SYNC;
+		*status |= FE_HAS_SIGNAL;
+	}
+
+	return 0;
+}
+
+static int s921_read_ber(struct dvb_frontend *fe, __u32 *ber)
+{
+	dprintk("read ber\n");
+	return 0;
+}
+
+static int s921_read_snr(struct dvb_frontend *fe, __u16 *snr)
+{
+	dprintk("read snr\n");
+	return 0;
+}
+
+static int s921_read_ucblocks(struct dvb_frontend *fe, __u32 *ucblocks)
+{
+	dprintk("read ucblocks\n");
+	return 0;
+}
+
+static void s921_release(struct dvb_frontend *fe)
+{
+	struct s921_state *state = (struct s921_state *)fe->demodulator_priv;
+	kfree(state);
+}
+
+static struct dvb_frontend_ops demod_s921={
+	.info = {
+		.name			= "SHARP S921",
+		.type			= FE_OFDM,
+		.frequency_min		= 473143000,
+		.frequency_max		= 767143000,
+		.frequency_stepsize	=   6000000,
+		.frequency_tolerance	= 0,
+		.caps = FE_CAN_FEC_1_2 | FE_CAN_FEC_2_3 |
+			FE_CAN_FEC_3_4 | FE_CAN_FEC_5_6 | FE_CAN_FEC_7_8 |
+			FE_CAN_FEC_AUTO |
+			FE_CAN_QPSK | FE_CAN_QAM_16 | FE_CAN_QAM_64 | FE_CAN_QAM_AUTO |
+			FE_CAN_TRANSMISSION_MODE_AUTO | FE_CAN_GUARD_INTERVAL_AUTO |
+			FE_CAN_HIERARCHY_AUTO | FE_CAN_RECOVER |
+			FE_CAN_MUTE_TS
+	},
+	.init = s921_init,
+	.sleep = s921_sleep,
+	.set_frontend = s921_set_parameters,
+	.read_snr = s921_read_snr,
+	.read_ber = s921_read_ber,
+	.read_status = s921_read_status,
+	.read_ucblocks = s921_read_ucblocks,
+	.release = s921_release,
+};
+
+static int s921_write(void *dev, u8 reg, u8 val) {
+	struct s921_state *state = dev;
+	char buf[2]={reg,val};
+        int err;
+	struct i2c_msg i2cmsgs = {
+		.addr = state->addr,
+		.flags = 0,
+		.len = 2,
+		.buf = buf
+	};
+
+	if((err = i2c_transfer(state->i2c, &i2cmsgs, 1))<0) {
+		printk("%s i2c_transfer error %d\n", __FUNCTION__, err);
+                if (err < 0)
+                        return err;
+                else
+                        return -EREMOTEIO;
+        }
+
+	return 0;
+}
+
+static int s921_read(void *dev, u8 reg) {
+	struct s921_state *state = dev;
+	u8 b1;
+	int ret;
+	struct i2c_msg msg[2] = { { .addr = state->addr,
+				    .flags = 0,
+				    .buf = &reg, .len = 1 },
+				  { .addr = state->addr,
+				    .flags = I2C_M_RD,
+				    .buf = &b1, .len = 1 } };
+
+	ret = i2c_transfer(state->i2c, msg, 2);
+	if (ret != 2)
+		return ret;
+	return b1;
+}
+
+struct dvb_frontend* s921_attach(const struct s921_config *config,
+					   struct i2c_adapter *i2c)
+{
+
+	struct s921_state *state;
+	state = kzalloc(sizeof(struct s921_state), GFP_KERNEL);
+	memset(state, 0x0, sizeof(struct s921_state));
+
+	state->addr = config->i2c_address;
+	state->i2c = i2c;
+	state->dev.i2c_write = &s921_write;
+	state->dev.i2c_read = &s921_read;
+	state->dev.priv_dev = state;
+
+	s921_isdb_cmd(&state->dev, ISDB_T_CMD_INIT, NULL);
+
+	memcpy(&state->frontend.ops, &demod_s921, sizeof(struct dvb_frontend_ops));
+	state->frontend.demodulator_priv = state;
+	return &state->frontend;
+}
+
+EXPORT_SYMBOL_GPL(s921_attach);
+MODULE_AUTHOR("Markus Rechberger <mrechberger@empiatech.com>");
+MODULE_DESCRIPTION("Sharp S921 ISDB-T 1Seg");
+MODULE_LICENSE("GPL");

drivers/media/video/empia/sharp/s921_module.h

+/*
+ *  Driver for DVB-T s921 demodulator
+ *
+ *  Copyright (C) 2008 Markus Rechberger <mrechberger@sundtek.de>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.=
+ */
+
+#ifndef S921_MODULE_H
+#define S921_MODULE_H
+
+#include <linux/dvb/frontend.h>
+#include "s921_core.h"
+
+int s921_isdb_init(struct s921_isdb_t *dev);
+int s921_isdb_cmd(struct s921_isdb_t *dev, u32 cmd, void *data);
+
+struct s921_config
+{
+	/* demodulator's I2C address */
+	u8 i2c_address;
+};
+
+#if defined(CONFIG_DVB_S921) || (defined(CONFIG_DVB_S921_MODULE) && defined(MODULE))
+extern struct dvb_frontend* s921_attach(const struct s921_config *config,
+					   struct i2c_adapter *i2c);
+#else
+static inline struct dvb_frontend* s921_attach(const struct s921_config *config,
+					   struct i2c_adapter *i2c)
+{
+	printk(KERN_WARNING "%s: driver disabled by Kconfig\n", __func__);
+	return NULL;
+}
+#endif /* CONFIG_DVB_S921 */
+
+#endif /* S921_H */