[PATCH 3/3] media: Add support for the AM/FM radio chip KT0913 from KT Micro.

Santiago Hormazabal
2020-07-17T00:45:36Z

This chip requires almost no support components and can used over I2C.
The driver uses the I2C bus and exposes the controls as a V4L2 radio.
Tested with a module that contains this chip (from SZZSJDZ.com,
part number ZJ-801B) and a H2+ AllWinner SoC running the master
(at this time) of the media_tree.

Signed-off-by: Santiago Hormazabal <santiagohssl@gmail.com>
---
drivers/media/radio/radio-kt0913.c | 1181 ++++++++++++++++++++++++++++
1 file changed, 1181 insertions(+)
create mode 100644 drivers/media/radio/radio-kt0913.c

diff --git a/drivers/media/radio/radio-kt0913.c b/drivers/media/radio/radio-kt0913.c
new file mode 100644
index 000000000000..9350d1764d44
--- /dev/null
+++ b/drivers/media/radio/radio-kt0913.c
@@ -0,0 +1,1181 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * drivers/media/radio/radio-kt0913.c
+ *
+ * Driver for the KT0913 radio chip from KTMicro.
+ * This driver provides a v4l2 interface to the tuner, using the I2C
+ * protocol to communicate with the chip.
+ * It exposes two bands, one for AM and another for FM. If the "campus
+ * band" feature needs to be enabled, set the corresponding module parameter
+ * to 1.
+ * Reference Clock and Audio DAC anti-pop configurations should be
+ * set via a device tree node. Defaults will be used otherwise.
+ *
+ * Audio output should be routed to a speaker or an audio capture
+ * device.
+ *
+ * Based on radio-tea5764 by Fabio Belavenuto <belavenuto@gmail.com>
+ *
+ * Copyright (c) 2020 Santiago Hormazabal <santiagohssl@gmail.com>
+ *
+ * TODO:
+ * use rd and wr support for the regmap instead of volatile regs.
+ * add support for the hardware-assisted frequency seek.
+ * export FM SNR and AM/FM AFC deviation values as RO controls.
+ */
+
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/err.h>
+#include <linux/pm_runtime.h>
+#include <linux/of.h>
+#include <linux/math64.h>
+#include <linux/regmap.h>
+#include <media/v4l2-ctrls.h>
+#include <media/v4l2-device.h>
+#include <media/v4l2-ioctl.h>
+#include <media/v4l2-event.h>
+
+ /* ************************************************************************* */
+
+ /* registers of the kt0913 */
+#define KT0913_REG_CHIP_ID 0x01
+#define KT0913_REG_SEEK 0x02
+#define KT0913_REG_TUNE 0x03
+#define KT0913_REG_VOLUME 0x04
+#define KT0913_REG_DSPCFGA 0x05
+#define KT0913_REG_LOCFGA 0x0A
+#define KT0913_REG_LOCFGC 0x0C
+#define KT0913_REG_RXCFG 0x0F
+#define KT0913_REG_STATUSA 0x12
+#define KT0913_REG_STATUSB 0x13
+#define KT0913_REG_STATUSC 0x14
+#define KT0913_REG_AMSYSCFG 0x16
+#define KT0913_REG_AMCHAN 0x17
+#define KT0913_REG_AMCALI 0x18
+#define KT0913_REG_GPIOCFG 0x1D
+#define KT0913_REG_AMDSP 0x22
+#define KT0913_REG_AMSTATUSA 0x24
+#define KT0913_REG_AMSTATUSB 0x25
+#define KT0913_REG_SOFTMUTE 0x2E
+#define KT0913_REG_AMCFG 0x33
+#define KT0913_REG_AMCFG2 0x34
+#define KT0913_REG_AFC 0x3C
+
+/* register symbols masks, values and shift count */
+#define KT0913_TUNE_FMTUNE_MASK 0x8000 /* FM Tune enable */
+#define KT0913_TUNE_FMTUNE_ON 0x8000 /* FM Tune enabled */
+#define KT0913_TUNE_FMTUNE_OFF 0x0000 /* FM Tune disabled */
+#define KT0913_TUNE_FMCHAN_MASK 0x0FFF /* frequency in kHz / 50kHz */
+
+#define KT0913_VOLUME_DMUTE_MASK 0x2000
+#define KT0913_VOLUME_DMUTE_ON 0x0000
+#define KT0913_VOLUME_DMUTE_OFF 0x2000
+#define KT0913_VOLUME_DE_MASK 0x0800 /* de-emphasis time constant */
+#define KT0913_VOLUME_DE_75US 0x0000 /* 75us */
+#define KT0913_VOLUME_DE_50US 0x0800 /* 50us */
+#define KT0913_VOLUME_POP_MASK 0x30 /* audio dac anti-pop config */
+#define KT0913_VOLUME_POP_SHIFT 4
+
+#define KT0913_DSPCFGA_MONO_MASK 0x8000 /* mono select (0=stereo, 1=mono) */
+#define KT0913_DSPCFGA_MONO_ON 0x8000 /* mono */
+#define KT0913_DSPCFGA_MONO_OFF 0x0000 /* stereo */
+
+#define KT0913_LOCFG_CAMPUSBAND_EN_MASK 0x0008 /* campus band fm enable */
+#define KT0913_LOCFG_CAMPUSBAND_EN_ON 0x0008 /* FM range 64-110MHz */
+#define KT0913_LOCFG_CAMPUSBAND_EN_OFF 0x0000 /* FM range 32-110MHz */
+
+#define KT0913_RXCFGA_STDBY_MASK 0x1000 /* standby mode enable */
+#define KT0913_RXCFGA_STDBY_ON 0x1000 /* standby mode enabled */
+#define KT0913_RXCFGA_STDBY_OFF 0x0000 /* standby mode disabled */
+#define KT0913_RXCFGA_VOLUME_MASK 0x001F /* volume control */
+
+#define KT0913_STATUSA_XTAL_OK 0x8000 /* crystal ready indicator */
+#define KT0913_STATUSA_STC 0x4000 /* seek/tune complete */
+
+#define KT0913_STATUSA_PLL_LOCK_MASK 0x800 /* system pll ready indicator */
+#define KT0913_STATUSA_PLL_LOCK_LOCKED 0x800 /* system pll ready */
+#define KT0913_STATUSA_PLL_LOCK_UNLOCKED 0x000 /* not ready */
+#define KT0913_STATUSA_LO_LOCK 0x400 /* LO synthesizer ready indicator */
+#define KT0913_STATUSA_ST_MASK 0x300 /* stereo indicator (0x300=stereo, otherwise mono) */
+#define KT0913_STATUSA_ST_STEREO 0x300 /* stereo */
+#define KT0913_STATUSA_FMRSSI_MASK 0xF8 /* FM RSSI (-100dBm + FMRSSI*3dBm) */
+#define KT0913_STATUSA_FMRSSI_SHIFT 3
+
+#define KT0913_STATUSC_PWSTATUS 0x8000 /* power status indicator */
+#define KT0913_STATUSC_CHIPRDY 0x2000 /* chip ready indicator */
+#define KT0913_STATUSC_FMSNR 0x1FC0 /* FM SNR (unknown units) */
+
+#define KT0913_AMCHAN_AMTUNE_MASK 0x8000 /* AM tune enable */
+#define KT0913_AMCHAN_AMTUNE_ON 0x8000 /* AM tune enabled */
+#define KT0913_AMCHAN_AMTUNE_OFF 0x0000 /* AM tune disabled */
+#define KT0913_AMCHAN_AMCHAN_MASK 0x7FF /* am channel in kHz */
+
+#define KT0913_AMSYSCFG_AM_FM_MASK 0x8000 /* am/fm mode control */
+#define KT0913_AMSYSCFG_AM_FM_AM 0x8000 /* am mode */
+#define KT0913_AMSYSCFG_AM_FM_FM 0x0000 /* fm mode (default) */
+#define KT0913_AMSYSCFG_REFCLK_MASK 0x0F00 /* reference clock selection */
+#define KT0913_AMSYSCFG_REFCLK_SHIFT 8
+#define KT0913_AMSYSCFG_AU_GAIN_MASK 0x00C0 /* audio gain selection */
+#define KT0913_AMSYSCFG_AU_GAIN_6DB 0x0040 /* 6dB audio gain */
+#define KT0913_AMSYSCFG_AU_GAIN_3DB 0x0000 /* 3dB audio gain (default) */
+#define KT0913_AMSYSCFG_AU_GAIN_0DB 0x00C0 /* 0dB audio gain */
+#define KT0913_AMSYSCFG_AU_GAIN_MIN_3DB 0x0080 /* -3dB audio gain */
+
+#define KT0913_AMSTATUSA_AMRSSI_MASK 0x1F00 /* am channel rssi */
+#define KT0913_AMSTATUSA_AMRSSI_SHIFT 8
+
+/* constants */
+#define KT0913_CHIP_ID 0x544B /* ASCII of 'KT' */
+
+#define V4L2_KHZ_FREQ_MUL 16U /* v4l2 uses 16x the kHz value as their freq */
+#define KT0913_FMCHAN_MUL 50U /* kt0913 uses freqs with a 50kHz multiplier */
+#define KT0913_FM_RANGE_LOW_NO_CAMPUS 64000U /* 64MHz lower bound for FM */
+#define KT0913_FM_RANGE_LOW_CAMPUS 32000U /* 32MHz lower bound for campus FM */
+#define KT0913_FM_RANGE_HIGH 110000U /* 110MHz upper bound for FM */
+#define KT0913_AM_RANGE_LOW 500U /* 500kHz lower bound for AM */
+#define KT0913_AM_RANGE_HIGH 1710U /* 1710kHz upper bound for AM */
+
+#define KT0913_FM_AM_DRIVER_NAME "kt0913-fm-am"
+
+/* ************************************************************************* */
+
+/* v4l2 device number to use. -1 will assign the next free one */
+static int kt0913_v4l2_radio_nr = -1;
+/* use the extended range of FM down to 32MHz. disabled by default */
+static int kt0913_use_campus_band;
+
+/* ************************************************************************* */
+
+/* kt0913 status struct */
+struct kt0913_device {
+ struct v4l2_device v4l2_dev; /* main v4l2 struct */
+ struct i2c_client *client; /* I2C client */
+ struct video_device vdev; /* vide_device struct */
+ struct v4l2_ctrl_handler ctrl_handler; /* ctrl_handler struct */
+
+ /* V4L2 Controls */
+ struct v4l2_ctrl *ctrl_pll_lock; /* PLL lock */
+ struct v4l2_ctrl *ctrl_volume; /* Overall volume */
+ struct v4l2_ctrl *ctrl_au_gain; /* Audio Gain */
+ struct v4l2_ctrl *ctrl_mute; /* Master mute */
+ struct v4l2_ctrl *ctrl_deemphasis; /* Deemphasis */
+
+ /* current operation band (fm, fm_campus, am) */
+ unsigned int band;
+
+ /* audio dac anti-pop setting:
+ * 0 -> 100uF (default)
+ * 1 -> 60uF
+ * 2 -> 20uF
+ * 3 -> 10uF
+ */
+ unsigned int audio_anti_pop;
+
+ /*
+ * reference clock selection:
+ * 0 -> 32.768kHz (default)
+ * 1 -> 6.5MHz
+ * 2 -> 7.6MHz
+ * 3 -> 12MHz
+ * 4 -> 13MHz
+ * 5 -> 15.2MHz
+ * 6 -> 19.2MHz
+ * 7 -> 24MHz
+ * 8 -> 26MHz
+ * 9 -> 38kHz
+ */
+ unsigned int refclock_val;
+
+ /* Regmap */
+ struct regmap *regmap;
+
+ /* For core assisted locking */
+ struct mutex mutex;
+};
+
+/* ************************************************************************* */
+
+/* Regmap settings */
+static const struct regmap_range kt0913_regmap_all_registers_range[] = {
+ regmap_reg_range(0x01, 0x05),
+ regmap_reg_range(0x0A, 0x0A),
+ regmap_reg_range(0x0C, 0x0C),
+ regmap_reg_range(0x0F, 0x0F),
+ regmap_reg_range(0x12, 0x14),
+ regmap_reg_range(0x16, 0x18),
+ regmap_reg_range(0x1D, 0x1D),
+ regmap_reg_range(0x22, 0x22),
+ regmap_reg_range(0x24, 0x25),
+ regmap_reg_range(0x2E, 0x2F),
+ regmap_reg_range(0x30, 0x34),
+ regmap_reg_range(0x3A, 0x3A),
+ regmap_reg_range(0x3C, 0x3C),
+};
+
+static const struct regmap_access_table kt0913_all_registers_access_table = {
+ .yes_ranges = kt0913_regmap_all_registers_range,
+ .n_yes_ranges = ARRAY_SIZE(kt0913_regmap_all_registers_range),
+};
+
+static const struct reg_sequence kt0913_init_regs_to_defaults[] = {
+ /* Standby disabled, volume 0dB */
+ { KT0913_REG_RXCFG, 0x881F },
+ /* FM Channel spacing = 50kHz, Right & Left unmuted */
+ { KT0913_REG_SEEK, 0x000B },
+ /* Stereo, High Stereo/Mono blend level, blend disabled */
+ { KT0913_REG_DSPCFGA, 0x1000 },
+ /* FM AFC Enabled */
+ { KT0913_REG_LOCFGA, 0x0100 },
+ /* Campus band disabled by default */
+ { KT0913_REG_LOCFGC, 0x0024 },
+ /*
+ * FM mode, internal defined bands, clock from XT, 32.768kHz
+ * 3dB audio gain, AM AFC Enabled
+ */
+ { KT0913_REG_AMSYSCFG, 0x0002 },
+ /* Default AM freq = 504kHz */
+ { KT0913_REG_AMCHAN, 0x01F8},
+ /* VOL and CH GPIOs set to HiZ */
+ { KT0913_REG_GPIOCFG, 0x0000 },
+ /* AM Channel bandwidth = 6kHz, non-differential output */
+ { KT0913_REG_AMDSP, 0xAFC4 },
+ /*
+ * softmute is disabled on AM and FM, but set the defaults:
+ * strong softmute attn., slow softmute attack/recover,
+ * lowest AM softumte start level, almost the minimum
+ * softmute target volume, RSSI mode for softmute, lowest
+ * FM softmute start level
+ */
+ { KT0913_REG_SOFTMUTE, 0x0010 },
+ /* 1kHz for AM channel space, working mode A for the keys */
+ { KT0913_REG_AMCFG, 0x1401 },
+ /* TIME1 = shortest, TIME2 = fastest */
+ { KT0913_REG_AMCFG, 0x4050 },
+ /* set 86MHz as the default frequency, and tune it */
+ { KT0913_REG_TUNE, 0x86B8 },
+ /*
+ * FM&AM Softmute disabled, Mute disabled, 75us deemp.,
+ * no bass boost, 100uF anti pop cap
+ */
+ { KT0913_REG_VOLUME, 0xE080 },
+};
+
+static const struct regmap_config kt0913_regmap_config = {
+ .reg_bits = 8,
+ .val_bits = 16,
+ .max_register = KT0913_REG_AFC,
+ .volatile_table = &kt0913_all_registers_access_table,
+ .cache_type = REGCACHE_RBTREE,
+ .val_format_endian = REGMAP_ENDIAN_BIG,
+};
+
+/* ************************************************************************* */
+
+/* bands where the kt0913 operates */
+enum { BAND_FM, BAND_FM_CAMUS, BAND_AM };
+
+static const struct v4l2_frequency_band kt0913_bands[] = {
+ {
+ /* BAND_FM */
+ .type = V4L2_TUNER_RADIO,
+ .index = 0, /* index provided to v4l2 */
+ .capability = V4L2_TUNER_CAP_LOW | V4L2_TUNER_CAP_STEREO |
+ V4L2_TUNER_CAP_FREQ_BANDS,
+ .rangelow = KT0913_FM_RANGE_LOW_NO_CAMPUS * V4L2_KHZ_FREQ_MUL,
+ .rangehigh = KT0913_FM_RANGE_HIGH * V4L2_KHZ_FREQ_MUL,
+ .modulation = V4L2_BAND_MODULATION_FM,
+ },
+ {
+ /* BAND_FM_CAMUS */
+ .type = V4L2_TUNER_RADIO,
+ .index = 0, /* index provided to v4l2 */
+ .capability = V4L2_TUNER_CAP_LOW | V4L2_TUNER_CAP_STEREO |
+ V4L2_TUNER_CAP_FREQ_BANDS,
+ .rangelow = KT0913_FM_RANGE_LOW_CAMPUS * V4L2_KHZ_FREQ_MUL,
+ .rangehigh = KT0913_FM_RANGE_HIGH * V4L2_KHZ_FREQ_MUL,
+ .modulation = V4L2_BAND_MODULATION_FM,
+ },
+ {
+ /* BAND_AM */
+ .type = V4L2_TUNER_RADIO,
+ .index = 1, /* index provided to v4l2 */
+ .capability = V4L2_TUNER_CAP_LOW | V4L2_TUNER_CAP_FREQ_BANDS,
+ .rangelow = KT0913_AM_RANGE_LOW * V4L2_KHZ_FREQ_MUL,
+ .rangehigh = KT0913_AM_RANGE_HIGH * V4L2_KHZ_FREQ_MUL,
+ .modulation = V4L2_BAND_MODULATION_AM,
+ },
+};
+
+/* ************************************************************************* */
+
+static inline struct kt0913_device *v4l2_device_to_device(
+ struct v4l2_device *v4l2_dev)
+{
+ return container_of(v4l2_dev,
+ struct kt0913_device, v4l2_dev);
+}
+
+static inline struct kt0913_device *v4l2_ctrl_to_device(
+ struct v4l2_ctrl *ctrl_handler)
+{
+ return container_of(ctrl_handler->handler,
+ struct kt0913_device, ctrl_handler);
+}
+
+/* ************************************************************************* */
+
+static inline u32 khz_to_v4l2_freq(unsigned int freq)
+{
+ return freq * V4L2_KHZ_FREQ_MUL;
+}
+
+static inline unsigned int v4l2_freq_to_khz(u32 v4l2_freq)
+{
+ return v4l2_freq / V4L2_KHZ_FREQ_MUL;
+}
+
+/* ************************************************************************* */
+
+static int __kt0913_get_fm_frequency(struct kt0913_device *radio,
+ unsigned int *frequency)
+{
+ unsigned int tune_reg;
+ int ret = regmap_read(radio->regmap, KT0913_REG_TUNE, &tune_reg);
+
+ if (ret)
+ return ret;
+
+ *frequency = (tune_reg & KT0913_TUNE_FMCHAN_MASK) * KT0913_FMCHAN_MUL;
+
+ return 0;
+}
+
+static int __kt0913_set_fm_frequency(struct kt0913_device *radio,
+ unsigned int frequency)
+{
+ return regmap_write(radio->regmap, KT0913_REG_TUNE,
+ KT0913_TUNE_FMTUNE_ON | (frequency / KT0913_FMCHAN_MUL));
+}
+
+/* ************************************************************************* */
+
+static int __kt0913_set_mute(struct kt0913_device *radio, int on)
+{
+ return regmap_update_bits(radio->regmap,
+ KT0913_REG_VOLUME, KT0913_VOLUME_DMUTE_MASK,
+ on ? KT0913_VOLUME_DMUTE_ON : KT0913_VOLUME_DMUTE_OFF);
+}
+
+/* ************************************************************************* */
+
+static int __kt0913_set_deemphasis(struct kt0913_device *radio, s32 deemp)
+{
+ switch (deemp) {
+ case V4L2_DEEMPHASIS_75_uS:
+ return regmap_update_bits(radio->regmap,
+ KT0913_REG_VOLUME, KT0913_VOLUME_DE_MASK,
+ KT0913_VOLUME_DE_50US);
+
+ /* 50us is used for the disabled option (which is not supported
+ * on the chip) and the 50uS value
+ */
+ default:
+ return regmap_update_bits(radio->regmap,
+ KT0913_REG_VOLUME, KT0913_VOLUME_DE_MASK,
+ KT0913_VOLUME_DE_75US);
+ }
+}
+
+/* ************************************************************************* */
+
+static int __kt0913_set_volume(struct kt0913_device *radio, s32 volume)
+{
+ /* map [-60, 0] to [1, 31] which is what the kt0913 expects */
+ volume = (volume / 2) + 31;
+ return regmap_update_bits(radio->regmap,
+ KT0913_REG_RXCFG, KT0913_RXCFGA_VOLUME_MASK,
+ volume);
+}
+
+/* ************************************************************************* */
+
+static int __kt0913_set_standby(struct kt0913_device *radio, int standby)
+{
+ return regmap_update_bits(radio->regmap,
+ KT0913_REG_RXCFG, KT0913_RXCFGA_STDBY_MASK,
+ standby ? KT0913_RXCFGA_STDBY_ON : KT0913_RXCFGA_STDBY_OFF);
+}
+
+/* ************************************************************************* */
+
+static int __kt0913_get_pll_status(struct kt0913_device *radio, int *locked)
+{
+ unsigned int statusa_reg;
+ int ret = regmap_read(radio->regmap, KT0913_REG_STATUSA, &statusa_reg);
+
+ if (ret)
+ return ret;
+
+ *locked = (statusa_reg & KT0913_STATUSA_PLL_LOCK_MASK) ==
+ KT0913_STATUSA_PLL_LOCK_LOCKED ? 1 : 0;
+
+ return 0;
+}
+
+/* ************************************************************************* */
+
+static int __kt0913_get_rx_stereo_or_mono(struct kt0913_device *radio,
+ int *stereo)
+{
+ unsigned int statusa_reg;
+ int ret = regmap_read(radio->regmap, KT0913_REG_STATUSA, &statusa_reg);
+
+ if (ret)
+ return ret;
+
+ *stereo = (statusa_reg & KT0913_STATUSA_ST_MASK) ==
+ KT0913_STATUSA_ST_STEREO ? 1 : 0;
+
+ return 0;
+}
+
+/* ************************************************************************* */
+
+static int __kt0913_get_fm_rssi(struct kt0913_device *radio, s32 *rssi)
+{
+ unsigned int statusa_reg;
+ int ret = regmap_read(radio->regmap, KT0913_REG_STATUSA, &statusa_reg);
+
+ if (ret)
+ return ret;
+
+ /* RSSI(dBm) = -100 + FMRSSI<4:0> * 3dBm
+ * even tho we can get the value in dBm, we want a %
+ */
+ *rssi = (statusa_reg & KT0913_STATUSA_FMRSSI_MASK) >>
+ KT0913_STATUSA_FMRSSI_SHIFT;
+ /* map range 0-31 to 0-65535 */
+ *rssi *= 65535;
+ *rssi /= KT0913_STATUSA_FMRSSI_MASK >> KT0913_STATUSA_FMRSSI_SHIFT;
+
+ return 0;
+}
+
+/* ************************************************************************* */
+
+static int __kt0913_get_cfg_stereo_enabled(struct kt0913_device *radio,
+ int *stereo)
+{
+ unsigned int dspcfga_reg;
+ int ret = regmap_read(radio->regmap, KT0913_REG_DSPCFGA, &dspcfga_reg);
+
+ if (ret)
+ return ret;
+
+ *stereo = (dspcfga_reg & KT0913_DSPCFGA_MONO_MASK) ==
+ KT0913_DSPCFGA_MONO_OFF ? 1 : 0;
+
+ return ret;
+}
+
+static int __kt0913_set_cfg_stereo_enabled(struct kt0913_device *radio,
+ int stereo)
+{
+ return regmap_update_bits(radio->regmap,
+ KT0913_REG_DSPCFGA, KT0913_DSPCFGA_MONO_MASK,
+ stereo ? KT0913_DSPCFGA_MONO_OFF : KT0913_DSPCFGA_MONO_ON);
+}
+
+/* ************************************************************************* */
+
+static int __kt0913_set_au_gain(struct kt0913_device *radio, s32 gain)
+{
+ switch (gain) {
+ case 6:
+ return regmap_update_bits(radio->regmap,
+ KT0913_REG_AMSYSCFG, KT0913_AMSYSCFG_AU_GAIN_MASK,
+ KT0913_AMSYSCFG_AU_GAIN_6DB);
+ case 3:
+ return regmap_update_bits(radio->regmap,
+ KT0913_REG_AMSYSCFG, KT0913_AMSYSCFG_AU_GAIN_MASK,
+ KT0913_AMSYSCFG_AU_GAIN_3DB);
+ case 0:
+ return regmap_update_bits(radio->regmap,
+ KT0913_REG_AMSYSCFG, KT0913_AMSYSCFG_AU_GAIN_MASK,
+ KT0913_AMSYSCFG_AU_GAIN_0DB);
+ case -3:
+ return regmap_update_bits(radio->regmap,
+ KT0913_REG_AMSYSCFG, KT0913_AMSYSCFG_AU_GAIN_MASK,
+ KT0913_AMSYSCFG_AU_GAIN_MIN_3DB);
+ default:
+ return -EINVAL;
+ }
+}
+
+/* ************************************************************************* */
+
+static int __kt0913_set_am_fm_band(struct kt0913_device *radio,
+ unsigned int band)
+{
+ return regmap_update_bits(radio->regmap,
+ KT0913_REG_AMSYSCFG, KT0913_AMSYSCFG_AM_FM_MASK,
+ band == BAND_AM ?
+ KT0913_AMSYSCFG_AM_FM_AM : KT0913_AMSYSCFG_AM_FM_FM);
+}
+
+/* ************************************************************************* */
+
+static int __kt0913_get_am_frequency(struct kt0913_device *radio,
+ unsigned int *frequency)
+{
+ unsigned int amchan_reg;
+ int ret = regmap_read(radio->regmap, KT0913_REG_AMCHAN, &amchan_reg);
+
+ if (ret)
+ return ret;
+
+ *frequency = (amchan_reg & KT0913_AMCHAN_AMCHAN_MASK);
+
+ return 0;
+}
+
+static int __kt0913_set_am_frequency(struct kt0913_device *radio,
+ unsigned int frequency)
+{
+ return regmap_write(radio->regmap, KT0913_REG_AMCHAN,
+ KT0913_AMCHAN_AMTUNE_ON | frequency);
+}
+
+/* ************************************************************************* */
+
+static int __kt0913_get_am_rssi(struct kt0913_device *radio, s32 *rssi)
+{
+ unsigned int amstatusa_reg;
+ int ret = regmap_read(radio->regmap, KT0913_REG_AMSTATUSA, &amstatusa_reg);
+
+ if (ret)
+ return ret;
+
+ /* AMRSSI(dBm) = -90 + AMRSSI<4:0> * 3dBm
+ * even tho we can get the value in dBm, we want a %
+ */
+ *rssi = (amstatusa_reg & KT0913_AMSTATUSA_AMRSSI_MASK) >>
+ KT0913_AMSTATUSA_AMRSSI_SHIFT;
+ /* map range 0-31 to 0-65535 */
+ *rssi *= 65535;
+ *rssi /= KT0913_AMSTATUSA_AMRSSI_MASK >> KT0913_AMSTATUSA_AMRSSI_SHIFT;
+
+ return 0;
+}
+
+/* ************************************************************************* */
+
+static int __kt0913_init(struct kt0913_device *radio)
+{
+ int ret = 0;
+
+ /* write the defaults */
+ ret = regmap_multi_reg_write(radio->regmap,
+ kt0913_init_regs_to_defaults,
+ ARRAY_SIZE(kt0913_init_regs_to_defaults));
+ if (ret) {
+ v4l2_err(radio->client,
+ "regmap_multi_reg_write() failed! %d", ret);
+ return ret;
+ }
+
+ /* set the audio dac anti-pop config */
+ ret = regmap_update_bits(radio->regmap,
+ KT0913_REG_VOLUME, KT0913_VOLUME_POP_MASK,
+ radio->audio_anti_pop << KT0913_VOLUME_POP_SHIFT);
+ if (ret) {
+ v4l2_err(radio->client,
+ "regmap_update_bits() failed for anti-pop cfg! %d", ret);
+ return ret;
+ }
+
+ /* set the reference clock config */
+ ret = regmap_update_bits(radio->regmap,
+ KT0913_REG_AMSYSCFG, KT0913_AMSYSCFG_REFCLK_MASK,
+ radio->refclock_val << KT0913_AMSYSCFG_REFCLK_SHIFT);
+ if (ret) {
+ v4l2_err(radio->client,
+ "regmap_update_bits() failed for refclk cfg! %d", ret);
+ return ret;
+ }
+
+ if (kt0913_use_campus_band) {
+ v4l2_info(radio->client,
+ "campus band is enabled!");
+ /* set the campus band bit */
+ ret = regmap_update_bits(radio->regmap,
+ KT0913_REG_LOCFGC, KT0913_LOCFG_CAMPUSBAND_EN_MASK,
+ KT0913_LOCFG_CAMPUSBAND_EN_ON);
+ if (ret) {
+ v4l2_err(radio->client,
+ "regmap_update_bits() failed for campus band! %d",
+ ret);
+ return ret;
+ }
+ }
+
+ return __kt0913_set_mute(radio, true);
+}
+
+/* ************************************************************************* */
+
+static int kt0913_ioctl_vidioc_g_frequency(struct file *file, void *priv,
+ struct v4l2_frequency *f)
+{
+ struct kt0913_device *radio = video_drvdata(file);
+ int ret;
+
+ if (f->tuner != 0)
+ return -EINVAL;
+
+ f->type = V4L2_TUNER_RADIO;
+
+ if (radio->band == BAND_AM)
+ ret = __kt0913_get_am_frequency(radio, &f->frequency);
+ else
+ ret = __kt0913_get_fm_frequency(radio, &f->frequency);
+
+ if (ret)
+ return ret;
+
+ /* convert kHz freq into v4l2 freq */
+ f->frequency = khz_to_v4l2_freq(f->frequency);
+
+ return 0;
+}
+
+static int kt0913_ioctl_vidioc_s_frequency(struct file *file, void *priv,
+ const struct v4l2_frequency *f)
+{
+ struct kt0913_device *radio = video_drvdata(file);
+ unsigned int freq = f->frequency;
+ unsigned int new_band = BAND_FM;
+ int ret;
+
+ if (f->tuner != 0 || f->type != V4L2_TUNER_RADIO)
+ return -EINVAL;
+
+ if (freq == 0)
+ return -EINVAL;
+
+ /* check if the requested frequency is contained on the AM band */
+ if (freq <= kt0913_bands[BAND_AM].rangehigh)
+ new_band = BAND_AM;
+ else {
+ /* check if the requested frequency is contained on the FM band */
+ if (freq >= kt0913_bands[BAND_FM].rangelow)
+ new_band = BAND_FM;
+ /* check if the requested frequency is contained on the campus
+ * FM band only if that feature was enabled
+ */
+ else if (kt0913_use_campus_band &&
+ (freq >= kt0913_bands[BAND_FM_CAMUS].rangelow))
+ new_band = BAND_FM_CAMUS;
+ else {
+ v4l2_warn(radio->client,
+ "frequency out of allowed RF bands (%u kHz)",
+ v4l2_freq_to_khz(freq));
+ return -EINVAL;
+ }
+ }
+
+ /* is the requested band different than the one currently set? */
+ if (radio->band != new_band) {
+ ret = __kt0913_set_am_fm_band(radio, new_band);
+ if (ret)
+ return ret;
+ radio->band = new_band;
+ }
+
+ /* clamp the frequency to the band boundaries */
+ freq = clamp(freq, kt0913_bands[new_band].rangelow,
+ kt0913_bands[new_band].rangehigh);
+
+ /* convert v4l2 freq to kHz */
+ freq = v4l2_freq_to_khz(freq);
+
+ if (radio->band == BAND_AM)
+ return __kt0913_set_am_frequency(radio, freq);
+ else
+ return __kt0913_set_fm_frequency(radio, freq);
+}
+
+static int kt0913_ioctl_vidioc_enum_freq_bands(struct file *file, void *priv,
+ struct v4l2_frequency_band *band)
+{
+ if (band->tuner != 0)
+ return -EINVAL;
+
+ switch (band->index) {
+ case 0:
+ if (kt0913_use_campus_band)
+ *band = kt0913_bands[BAND_FM_CAMUS];
+ else
+ *band = kt0913_bands[BAND_FM];
+ return 0;
+ case 1:
+ *band = kt0913_bands[BAND_AM];
+ return 0;
+ default:
+ return -EINVAL;
+ }
+}
+
+/* ************************************************************************* */
+
+/* V4L2 vidioc */
+static int kt0913_ioctl_vidioc_querycap(struct file *file, void *priv,
+ struct v4l2_capability *capability)
+{
+ struct kt0913_device *radio = video_drvdata(file);
+ struct video_device *dev;
+
+ if (!radio)
+ return -ENODEV;
+
+ dev = &radio->vdev;
+
+ if (!dev)
+ return -ENODEV;
+
+ strscpy(capability->driver, KT0913_FM_AM_DRIVER_NAME,
+ sizeof(capability->driver));
+ strscpy(capability->card, dev->name, sizeof(capability->card));
+ snprintf(capability->bus_info, sizeof(capability->bus_info),
+ "I2C:%s", dev_name(&dev->dev));
+ return 0;
+}
+
+static int kt0913_ioctl_vidioc_g_tuner(struct file *file, void *priv,
+ struct v4l2_tuner *v)
+{
+ struct kt0913_device *radio = video_drvdata(file);
+ int ret;
+ int stereo_enabled;
+ int is_stereo;
+
+ if (v->index != 0)
+ return -EINVAL;
+
+ strscpy(v->name, "FM/AM", sizeof(v->name));
+ v->type = V4L2_TUNER_RADIO;
+
+ v->capability = V4L2_TUNER_CAP_LOW | V4L2_TUNER_CAP_STEREO |
+ V4L2_TUNER_CAP_FREQ_BANDS;
+
+ v->rangelow = kt0913_bands[BAND_AM].rangelow;
+ v->rangehigh = kt0913_bands[BAND_FM].rangehigh;
+
+ if (radio->band == BAND_AM) {
+ v->rxsubchans = V4L2_TUNER_SUB_MONO;
+ v->audmode = V4L2_TUNER_MODE_MONO;
+
+ ret = __kt0913_get_am_rssi(radio, &v->signal);
+ if (ret)
+ return ret;
+ } else {
+ ret = __kt0913_get_cfg_stereo_enabled(radio, &stereo_enabled);
+ if (ret)
+ return ret;
+
+ v->rxsubchans = stereo_enabled ?
+ V4L2_TUNER_SUB_STEREO : V4L2_TUNER_SUB_MONO;
+
+ ret = __kt0913_get_rx_stereo_or_mono(radio, &is_stereo);
+ if (ret)
+ return ret;
+
+ v->audmode = is_stereo ?
+ V4L2_TUNER_MODE_STEREO : V4L2_TUNER_MODE_MONO;
+
+ ret = __kt0913_get_fm_rssi(radio, &v->signal);
+ if (ret)
+ return ret;
+ }
+
+ /* AFC is enabled and active by default */
+ v->afc = 1;
+
+ return 0;
+}
+
+static int kt0913_ioctl_vidioc_s_tuner(struct file *file, void *priv,
+ const struct v4l2_tuner *v)
+{
+ struct kt0913_device *radio = video_drvdata(file);
+
+ if (v->index != 0)
+ return -EINVAL;
+
+ /* only mono and stereo are supported */
+ if (v->audmode != V4L2_TUNER_MODE_MONO &&
+ v->audmode != V4L2_TUNER_MODE_STEREO)
+ return 0;
+
+ /* AM is mono only, so don't try to set it to stereo */
+ if (radio->band == BAND_AM && v->audmode != V4L2_TUNER_MODE_MONO)
+ return 0;
+
+ /* set to stereo if specified, otherwise set to mono */
+ return __kt0913_set_cfg_stereo_enabled(radio,
+ v->audmode == V4L2_TUNER_MODE_STEREO);
+}
+
+static int kt0913_s_ctrl(struct v4l2_ctrl *ctrl)
+{
+ struct kt0913_device *radio = v4l2_ctrl_to_device(ctrl);
+
+ switch (ctrl->id) {
+ case V4L2_CID_AUDIO_MUTE:
+ return __kt0913_set_mute(radio, ctrl->val);
+ case V4L2_CID_AUDIO_VOLUME:
+ return __kt0913_set_volume(radio, ctrl->val);
+ case V4L2_CID_GAIN:
+ return __kt0913_set_au_gain(radio, ctrl->val);
+ case V4L2_CID_TUNE_DEEMPHASIS:
+ return __kt0913_set_deemphasis(radio, ctrl->val);
+ default:
+ return -EINVAL;
+ }
+}
+
+static int kt0913_g_volatile_ctrl(struct v4l2_ctrl *ctrl)
+{
+ struct kt0913_device *radio = v4l2_ctrl_to_device(ctrl);
+
+ switch (ctrl->id) {
+ case V4L2_CID_RF_TUNER_PLL_LOCK:
+ return __kt0913_get_pll_status(radio, &ctrl->val);
+ default:
+ return -EINVAL;
+ }
+}
+
+static const struct v4l2_ctrl_ops kt0913_ctrl_ops = {
+ .s_ctrl = kt0913_s_ctrl,
+ .g_volatile_ctrl = kt0913_g_volatile_ctrl,
+};
+
+/* ************************************************************************* */
+
+/* File system interface (use the ancillary fops for v4l2) */
+static const struct v4l2_file_operations kt0913_radio_fops = {
+ .owner = THIS_MODULE,
+ .open = v4l2_fh_open,
+ .release = v4l2_fh_release,
+ .poll = v4l2_ctrl_poll,
+ .unlocked_ioctl = video_ioctl2,
+};
+
+/* ioctl ops */
+static const struct v4l2_ioctl_ops kt0913_ioctl_ops = {
+ .vidioc_querycap = kt0913_ioctl_vidioc_querycap,
+ .vidioc_g_tuner = kt0913_ioctl_vidioc_g_tuner,
+ .vidioc_s_tuner = kt0913_ioctl_vidioc_s_tuner,
+ .vidioc_g_frequency = kt0913_ioctl_vidioc_g_frequency,
+ .vidioc_s_frequency = kt0913_ioctl_vidioc_s_frequency,
+ .vidioc_enum_freq_bands = kt0913_ioctl_vidioc_enum_freq_bands,
+ /* use ancillary functions for these: */
+ .vidioc_log_status = v4l2_ctrl_log_status,
+ .vidioc_subscribe_event = v4l2_ctrl_subscribe_event,
+ .vidioc_unsubscribe_event = v4l2_event_unsubscribe,
+};
+
+/* V4L2 RADIO device structure */
+static struct video_device kt0913_radio_template = {
+ .name = KT0913_FM_AM_DRIVER_NAME,
+ .fops = &kt0913_radio_fops,
+ .ioctl_ops = &kt0913_ioctl_ops,
+ .release = video_device_release_empty,
+ .vfl_dir = VFL_DIR_RX,
+ .device_caps = V4L2_CAP_TUNER | V4L2_CAP_RADIO,
+};
+
+/* ************************************************************************* */
+
+#if IS_ENABLED(CONFIG_OF)
+static const struct of_device_id kt0913_of_match[] = {
+ {.compatible = "ktm,kt0913" },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, kt0913_of_match);
+#endif /* IS_ENABLED(CONFIG_OF) */
+
+static void __kt0913_parse_dt(struct kt0913_device *radio)
+{
+ const void *ptr_anti_pop = of_get_property(radio->client->dev.of_node,
+ "ktm,anti-pop", NULL);
+ const void *ptr_refclk = of_get_property(radio->client->dev.of_node,
+ "ktm,refclk", NULL);
+
+ if (ptr_anti_pop) {
+ radio->audio_anti_pop =
+ clamp(be32_to_cpup(ptr_anti_pop), 0U, 3U);
+ } else {
+ radio->audio_anti_pop = 0;
+ v4l2_warn(radio->client,
+ "No ktm,anti-pop on dt node, using default");
+ }
+
+ if (ptr_refclk) {
+ radio->refclock_val =
+ clamp(be32_to_cpup(ptr_refclk), 0U, 9U);
+ } else {
+ radio->refclock_val = 0;
+ v4l2_warn(radio->client,
+ "No ktm,refclk on dt node, using default");
+ }
+}
+
+/* ************************************************************************* */
+
+static int kt0913_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ struct kt0913_device *radio;
+ struct v4l2_device *v4l2_dev;
+ struct v4l2_ctrl_handler *hdl;
+ struct regmap *regmap;
+ int ret;
+
+ pr_debug("%s\n", __func__);
+
+ /* this driver uses word R/W i2c operations, check if it's supported */
+ if (!i2c_check_functionality(client->adapter,
+ I2C_FUNC_SMBUS_READ_WORD_DATA | I2C_FUNC_SMBUS_WRITE_WORD_DATA)) {
+ v4l2_err(client,
+ "I2C adapter doesn't support word operations");
+ return -EIO;
+ }
+
+ /* check if the device exist on the bus before initializing it */
+ ret = i2c_smbus_read_word_data(client, KT0913_REG_CHIP_ID);
+ if (ret < 0) {
+ v4l2_err(client,
+ "Error reading CHIP ID of the kt0913 (%d)", ret);
+ return ret;
+ }
+
+ /* check if the CHIP ID register value matches the expected value */
+ if (ret != KT0913_CHIP_ID) {
+ v4l2_err(radio->client,
+ "Invalid CHIP ID: 0x%x, expected 0x%x", ret, KT0913_CHIP_ID);
+ return -ENODEV;
+ }
+
+ v4l2_info(client,
+ "kt0913 found @ 0x%x (%s)\n",
+ client->addr, client->adapter->name);
+
+ /* alloc context for the kt0913 radio struct */
+ radio = devm_kzalloc(&client->dev, sizeof(*radio), GFP_KERNEL);
+ if (!radio)
+ return -ENOMEM;
+
+ v4l2_dev = &radio->v4l2_dev;
+ ret = v4l2_device_register(&client->dev, v4l2_dev);
+ if (ret < 0) {
+ v4l2_err(client,
+ "could not register v4l2_dev\n");
+ goto errfr;
+ }
+
+ mutex_init(&radio->mutex);
+
+ /* register the control handler from the context struct */
+ hdl = &radio->ctrl_handler;
+ v4l2_ctrl_handler_init(hdl, 5);
+
+ /* add the control: Mute */
+ radio->ctrl_mute = v4l2_ctrl_new_std(hdl, &kt0913_ctrl_ops,
+ V4L2_CID_AUDIO_MUTE, 0, 1, 1, 0);
+ if (hdl->error) {
+ ret = hdl->error;
+ v4l2_err(v4l2_dev, "Could not register control: mute\n");
+ goto errunreg;
+ }
+
+ /* add the control: Volume */
+ radio->ctrl_volume = v4l2_ctrl_new_std(hdl, &kt0913_ctrl_ops,
+ V4L2_CID_AUDIO_VOLUME, -60, 0, 2, 0);
+ if (hdl->error) {
+ ret = hdl->error;
+ v4l2_err(v4l2_dev, "Could not register control: Volume\n");
+ goto errunreg;
+ }
+
+ /* add the control: audio gain */
+ radio->ctrl_au_gain = v4l2_ctrl_new_std(hdl, &kt0913_ctrl_ops,
+ V4L2_CID_GAIN, -3, 6, 3, 3);
+ if (hdl->error) {
+ ret = hdl->error;
+ v4l2_err(v4l2_dev, "Could not register control: audio gain\n");
+ goto errunreg;
+ }
+ radio->ctrl_au_gain->flags |= V4L2_CTRL_FLAG_SLIDER;
+
+ /* add the control: PLL Lock */
+ radio->ctrl_pll_lock = v4l2_ctrl_new_std(hdl, &kt0913_ctrl_ops,
+ V4L2_CID_RF_TUNER_PLL_LOCK, 0, 1, 1, 0);
+ if (hdl->error) {
+ ret = hdl->error;
+ v4l2_err(v4l2_dev, "Could not register control: pll lock\n");
+ goto errunreg;
+ }
+ radio->ctrl_pll_lock->flags |= (V4L2_CTRL_FLAG_VOLATILE |
+ V4L2_CTRL_FLAG_READ_ONLY);
+
+ /* add the control: deemphasis */
+ radio->ctrl_deemphasis = v4l2_ctrl_new_std_menu(hdl, &kt0913_ctrl_ops,
+ V4L2_CID_TUNE_DEEMPHASIS, V4L2_DEEMPHASIS_75_uS,
+ 0, V4L2_DEEMPHASIS_75_uS);
+ if (hdl->error) {
+ ret = hdl->error;
+ v4l2_err(v4l2_dev, "Could not register control: deemphasis\n");
+ goto errunreg;
+ }
+ /* the control handler is ready to be used */
+ v4l2_dev->ctrl_handler = hdl;
+
+ radio->vdev = kt0913_radio_template;
+ radio->vdev.lock = &radio->mutex;
+ radio->vdev.v4l2_dev = v4l2_dev;
+ video_set_drvdata(&radio->vdev, radio);
+
+ radio->client = client;
+ i2c_set_clientdata(client, radio);
+
+ /* init the regmap of the kt0913 */
+ regmap = devm_regmap_init_i2c(client, &kt0913_regmap_config);
+ if (IS_ERR(regmap)) {
+ ret = PTR_ERR(regmap);
+ v4l2_err(client,
+ "devm_regmap_init_i2c() failed! %d", ret);
+ goto errunreg;
+ }
+ radio->regmap = regmap;
+
+ __kt0913_parse_dt(radio);
+
+ /* init the kt0913 into a known state */
+ ret = __kt0913_init(radio);
+ if (ret) {
+ v4l2_err(client,
+ "__kt0913_init() failed! %d", ret);
+ goto errunreg;
+ }
+
+ pm_runtime_get_noresume(&client->dev);
+ pm_runtime_set_active(&client->dev);
+ pm_runtime_enable(&client->dev);
+ pm_runtime_dont_use_autosuspend(&client->dev);
+
+ ret = video_register_device(&radio->vdev,
+ VFL_TYPE_RADIO, kt0913_v4l2_radio_nr);
+ if (ret < 0) {
+ v4l2_err(client,
+ "Could not register video device!");
+ goto error_pm_disable;
+ }
+
+ v4l2_info(client, "registered.");
+ return 0;
+error_pm_disable:
+ pm_runtime_disable(&client->dev);
+ pm_runtime_set_suspended(&client->dev);
+errunreg:
+ v4l2_ctrl_handler_free(hdl);
+ v4l2_device_unregister(v4l2_dev);
+errfr:
+ __kt0913_set_standby(radio, true);
+ kfree(radio);
+ return ret;
+}
+
+static int kt0913_remove(struct i2c_client *client)
+{
+ struct kt0913_device *radio = i2c_get_clientdata(client);
+
+ pr_debug("%s\n", __func__);
+ if (!radio)
+ return -EINVAL;
+
+ __kt0913_set_standby(radio, true);
+
+ pm_runtime_get_sync(&client->dev);
+ pm_runtime_disable(&client->dev);
+ pm_runtime_set_suspended(&client->dev);
+ pm_runtime_put_noidle(&client->dev);
+
+ video_unregister_device(&radio->vdev);
+ v4l2_ctrl_handler_free(&radio->ctrl_handler);
+ v4l2_device_unregister(&radio->v4l2_dev);
+
+ v4l2_info(client, "removed.");
+ return 0;
+}
+
+/* ************************************************************************* */
+
+#ifdef CONFIG_PM
+static int kt0913_i2c_pm_runtime_suspend(struct device *dev)
+{
+ struct kt0913_device *radio = i2c_get_clientdata(to_i2c_client(dev));
+
+ pr_debug("%s\n", __func__);
+ if (!radio)
+ return 0;
+
+ return __kt0913_set_standby(radio, true);
+}
+
+static int kt0913_i2c_pm_runtime_resume(struct device *dev)
+{
+ struct kt0913_device *radio = i2c_get_clientdata(to_i2c_client(dev));
+
+ pr_debug("%s\n", __func__);
+ if (!radio)
+ return 0;
+
+ return __kt0913_set_standby(radio, false);
+}
+#endif /* CONFIG_PM */
+
+static const struct dev_pm_ops kt0913_i2c_pm_ops = {
+ SET_RUNTIME_PM_OPS(kt0913_i2c_pm_runtime_suspend,
+ kt0913_i2c_pm_runtime_resume, NULL)
+};
+
+static const struct i2c_device_id kt0913_idtable[] = {
+ { "kt0913", 0 },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, kt0913_idtable);
+
+static struct i2c_driver kt0913_driver = {
+ .driver = {
+ .name = "kt0913",
+ .of_match_table = of_match_ptr(kt0913_of_match),
+ .pm = &kt0913_i2c_pm_ops,
+ },
+ .probe = kt0913_probe,
+ .remove = kt0913_remove,
+ .id_table = kt0913_idtable,
+};
+module_i2c_driver(kt0913_driver);
+
+MODULE_AUTHOR("Santiago Hormazabal <santiagohssl@gmail.com>");
+MODULE_DESCRIPTION("KTMicro KT0913 AM/FM receiver");
+MODULE_LICENSE("GPL");
+MODULE_VERSION("0.0.1");
+
+module_param(kt0913_use_campus_band, int, 0);
+MODULE_PARM_DESC(kt0913_use_campus_band, "Use the Campus Band feature (FM range 32MHz-110MHz)");
+module_param(kt0913_v4l2_radio_nr, int, 0);
+MODULE_PARM_DESC(kt0913_v4l2_radio_nr, "v4l2 device number to use (i.e. /dev/radioX)");
--
2.24.1