Samsung YP-R0/YP-R1: use Linux i2c-dev for radio chip access

Linux offers the high-level i2c-dev driver to directly access the
i2c bus(ses) on the system. This system device is used to get rid
of the (rather silly) radio chip kernel module for ypr0 target and
correctly enables radio access also for the ypr1 target.
fm-radio chip is located on i2c-0 bus on the ypr0 target while it
is located on i2c-1 bus on the ypr1 target.
Power-up (RST) pin is also handled for both targets, which is wired
to another GPIO of the i.MX 37 platform.
Additionally, this patch simplifies the RDS low-level handling by
exploiting the Si4709 debug interface which comes with a mutex
protection as free bonus.

Change-Id: I839282bec4a27ad0ad8403c5a8dd86963b77e1bf

1 files changed, 83 insertions, 23 deletions

diff --git a/firmware/target/hosted/samsungypr/radio-ypr.c b/firmware/target/hosted/samsungypr/radio-ypr.c
index 4fccf2616f..42d485231d 100644
--- a/firmware/target/hosted/samsungypr/radio-ypr.c
+++ b/firmware/target/hosted/samsungypr/radio-ypr.c
@@ -21,58 +21,116 @@
  *
  ****************************************************************************/
 
+/* system includes */
 #include <unistd.h>
 #include <fcntl.h>
 #include <sys/ioctl.h>
+#include <linux/i2c-dev.h>
 #include "stdint.h"
 #include "string.h"
-#include "kernel.h"
 
+/* application includes */
+#include "kernel.h"
 #include "radio-ypr.h"
-#include "si4700.h"
 #include "power.h"
+#include "gpio-target.h"
+#include "gpio-ypr.h"
+#include "panic.h"
+#include "i2c-target.h"
+
+/* 7bits I2C address for Si4709
+ * (apparently not selectable by pins or revisions) */
+#define SI4709_I2C_SLAVE_ADDR   0x10
 
+/** i2c file handle */
 static int radio_dev = -1;
 
-void radiodev_open(void) {
-    radio_dev = open("/dev/si470x", O_RDWR);
+/* toggle radio RST pin */
+static void power_toggle(bool set)
+{
+    /* setup the GPIO port, as in OF */
+    gpio_set_iomux(GPIO_FM_BUS_EN, CONFIG_ALT3);
+    gpio_set_pad(GPIO_FM_BUS_EN, PAD_CTL_SRE_FAST | PAD_CTL_DRV_HIGH);
+    gpio_direction_output(GPIO_FM_BUS_EN);
+    gpio_set(GPIO_FM_BUS_EN, set);
 }
 
-void radiodev_close(void) {
-    close(radio_dev);
-}
+void radiodev_open(void)
+{
+    int retval = -1;    /* ioctl return value */
+
+    /* open the I2C bus where the chip is attached to */
+    radio_dev = open(I2C_BUS_FM_RADIO, O_RDWR);
+
+    if (radio_dev == -1)
+    {
+        panicf("%s: failed to open /dev/i2c-1 device - %d", __FUNCTION__, retval);
+    }
+    else
+    {
+        /* device is open, go on */
+
+        /* set the slave address for the handle.
+         * Some other modules might have set the same slave address
+         * e.g. another module. Let's do a I2C_SLAVE_FORCE which does
+         * not care about looking for other init'ed i2c slaves */
+        retval = ioctl(radio_dev, I2C_SLAVE_FORCE, SI4709_I2C_SLAVE_ADDR);
+
+        if (retval == -1)
+        {
+            /* the ioctl call should never fail, if radio_dev is valid */
+            panicf("%s: failed to set slave address - %d", __FUNCTION__, retval);
+        }
+        else
+        {
+            /* initialization completed */
+        }
+    }
+
+    /* i2c subsystem ready, now toggle power to the chip */
+    power_toggle(true);
+    /* 100ms reset delay */
+    sleep(HZ/10);
 
-/* High-level registers access */
-void si4709_write_reg(int addr, uint16_t value) {
-    sSi4709_t r = { .addr = addr, .value = value };
-    ioctl(radio_dev, IOCTL_SI4709_WRITE_BYTE, &r);
 }
 
-uint16_t si4709_read_reg(int addr) {
-    sSi4709_t r = { .addr = addr, .value = 0 };
-    ioctl(radio_dev, IOCTL_SI4709_READ_BYTE, &r);
-    return r.value;
+void radiodev_close(void)
+{
+    /* power the chip down */
+    power_toggle(false);
+
+    /* close the i2c subsystem */
+    if (radio_dev != -1)
+    {
+        (void)close(radio_dev);
+    }
+    else
+    {
+        /* not opened */
+    }
+
+    /* set back to safe error value */
+    radio_dev = -1;
 }
 
-/* Low-level i2c channel access */
+/* Low-level i2c channel access: write */
 int fmradio_i2c_write(unsigned char address, unsigned char* buf, int count)
 {
     (void)address;
-    sSi4709_i2c_t r = { .size = count, .buf = buf };
-    return ioctl(radio_dev, IOCTL_SI4709_I2C_WRITE, &r);
+    return write(radio_dev, buf, count);
 }
 
+/* Low-level i2c channel access: read */
 int fmradio_i2c_read(unsigned char address, unsigned char* buf, int count)
 {
     (void)address;
-    sSi4709_i2c_t r = { .size = count, .buf = buf };
-    return ioctl(radio_dev, IOCTL_SI4709_I2C_READ, &r);
+    return read(radio_dev, buf, count);
 }
 
 #ifdef HAVE_RDS_CAP
 
 /* Register we are going to poll */
-#define STATUSRSSI  0xA
+#define STATUSRSSI          (0xA)
 #define STATUSRSSI_RDSR     (0x1 << 15)
 
 /* Low-level RDS Support */
@@ -89,6 +147,7 @@ static void NORETURN_ATTR rds_thread(void)
     int timeout = TIMEOUT_BLOCK;
     struct queue_event ev;
     bool rds_rdy = false;
+    struct si4700_dbg_info radio_regs;
 
     while (true) {
         queue_wait_w_tmo(&rds_queue, &ev, timeout);
@@ -97,9 +156,10 @@ static void NORETURN_ATTR rds_thread(void)
                 /* power up: timeout after 1 tick, else block indefinitely */
                 timeout = ev.data ? 1 : TIMEOUT_BLOCK;
                 break;
-            case SYS_TIMEOUT:;
+            case SYS_TIMEOUT:
                 /* Captures RDS data and processes it */
-                bool rdsr = si4709_read_reg(STATUSRSSI) & STATUSRSSI_RDSR;
+                si4700_dbg_info(&radio_regs);
+                bool rdsr = radio_regs.regs[STATUSRSSI] & STATUSRSSI_RDSR;
                 if (rdsr != rds_rdy) {
                     rds_rdy = rdsr;
                     if (rdsr) {