clk: x86: Do not gate clocks enabled by the firmware

Read the enable register to determine if the clock is already in use by
the firmware. In this case avoid gating the clock.

Tested-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Darren Hart (VMware) <dvhart@infradead.org>
Signed-off-by: Carlo Caione <carlo@endlessm.com>
Fixes: 282a4e4ce5f9 ("platform/x86: Enable Atom PMC platform clocks")
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

diff --git a/drivers/clk/x86/clk-pmc-atom.c b/drivers/clk/x86/clk-pmc-atom.c
index f99abc1..08ef699 100644 (file)
--- a/drivers/clk/x86/clk-pmc-atom.c
+++ b/drivers/clk/x86/clk-pmc-atom.c
@@ -186,6 +186,13 @@ static struct clk_plt *plt_clk_register(struct platform_device *pdev, int id,
        pclk->reg = base + PMC_CLK_CTL_OFFSET + id * PMC_CLK_CTL_SIZE;
        spin_lock_init(&pclk->lock);
 
+       /*
+        * If the clock was already enabled by the firmware mark it as critical
+        * to avoid it being gated by the clock framework if no driver owns it.
+        */
+       if (plt_clk_is_enabled(&pclk->hw))
+               init.flags |= CLK_IS_CRITICAL;
+
        ret = devm_clk_hw_register(&pdev->dev, &pclk->hw);
        if (ret) {
                pclk = ERR_PTR(ret);