clk: imx: add common logic to detect early UART usage

Both earlycon and eralyprintk depend on the bootloader setup UART
clocks being retained. This patch adds the common logic to detect such
situations and make the information available to the clock drivers, as
well as adding the facilities to disable those clocks at the end of
the kernel init.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

diff --git a/drivers/clk/imx/clk.c b/drivers/clk/imx/clk.c
index df12b53071752955d533f20391d1a26a2a4dcd1e..a634b1185be38a1b5cd34dc93c23983a37448f0c 100644 (file)
--- a/drivers/clk/imx/clk.c
+++ b/drivers/clk/imx/clk.c
@@ -73,3 +73,41 @@ void imx_cscmr1_fixup(u32 *val)
        *val ^= CSCMR1_FIXUP;
        return;
 }
+
+static int imx_keep_uart_clocks __initdata;
+static struct clk ** const *imx_uart_clocks __initdata;
+
+static int __init imx_keep_uart_clocks_param(char *str)
+{
+       imx_keep_uart_clocks = 1;
+
+       return 0;
+}
+__setup_param("earlycon", imx_keep_uart_earlycon,
+             imx_keep_uart_clocks_param, 0);
+__setup_param("earlyprintk", imx_keep_uart_earlyprintk,
+             imx_keep_uart_clocks_param, 0);
+
+void __init imx_register_uart_clocks(struct clk ** const clks[])
+{
+       if (imx_keep_uart_clocks) {
+               int i;
+
+               imx_uart_clocks = clks;
+               for (i = 0; imx_uart_clocks[i]; i++)
+                       clk_prepare_enable(*imx_uart_clocks[i]);
+       }
+}
+
+static int __init imx_clk_disable_uart(void)
+{
+       if (imx_keep_uart_clocks && imx_uart_clocks) {
+               int i;
+
+               for (i = 0; imx_uart_clocks[i]; i++)
+                       clk_disable_unprepare(*imx_uart_clocks[i]);
+       }
+
+       return 0;
+}
+late_initcall_sync(imx_clk_disable_uart);

diff --git a/drivers/clk/imx/clk.h b/drivers/clk/imx/clk.h
index 1049b0c7d81829eb78ea21c8bec356e15f4dbd2b..c94ac5c26226df1edadfef4ebf1a0ac829c84c14 100644 (file)
--- a/drivers/clk/imx/clk.h
+++ b/drivers/clk/imx/clk.h
@@ -7,6 +7,7 @@
 extern spinlock_t imx_ccm_lock;
 
 void imx_check_clocks(struct clk *clks[], unsigned int count);
+void imx_register_uart_clocks(struct clk ** const clks[]);
 
 extern void imx_cscmr1_fixup(u32 *val);