Apple uses its own applications processors, but buys in the rest of its silicon.
Ad all of those are either standard parts like flash and dram built by companies specialized in those products (the battle in ram is over. Micron has won. The battle in flash is almost over. It's samsung or toshiba) or are devices sold for sub 1 $ prices. All those gps , wifi , bluetooth, position sensors, guroscopes, magnetometers, proximity sensors and other stuff all are sub one dollar pricepoint. Profit margins is diddly squat.
Flash and ram are auto generated by computer programs. Virtually no design work.
The rest is under sever price crunch. There are one or two other asics like the pmic that are interesting to work on but are also under severe price pressure.
Samsung makes some phones with its own applications processors, but seems to make far more with Qualcomm silicon in them.
Chinese makers like HuaWei, and ZTE are finally getting in gear and shipping large numbers of phones, all with Qualcomm or MTK silicon. They are really kicking Samsung's butt right now in China.
Qualcomm is a highly specialized company only doing one thing. I am talking from the perspective of an allround semiconductor house like TI or ST. They both pulled out of this market completely.
For tablets the picture is similar to the above, but numerous Chinese makers also use Rockchip and Allwinner devices by the shed load.
All fabless companies...
What i am saying is that the time of the power-house semiconductor companies that had a wide product portfolio , and has their own fabs and did everything end to end whether asic, analog , digital or mixed mode, is over.
It's highly specialised , one-trick pony , fabless joints that rise, are productive for a few years and then either disappear or get borged, and humongous designless fabs. Shove in masks and empty wafer and out comes chips.
Neither maxim nor linear nor analog devices still own fabs ...
The lucrative business in the tablet market or smartphone market would be the apps processor. Those are dominated by apples ons cpu or the samsung cpu and the qualcomm stuff fills the gap. Those others get to pick at the remaining 5% of the world market.... For the 'old skool powerhouses' that is a pond they can't even fish in ! The overhead is too large for them to turn a profit.
I am in this industry. The writing is on the wall...