tegra: add clock_ll_start_uart() to enable UART prior to reloc

Most boards will want to enable a UART early. This function provides
that feature in Tegra architecture code so the code does not need to be
copied on every board.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Tom Warren <twarren@nvidia.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/arch/arm/cpu/armv7/tegra2/clock.c b/arch/arm/cpu/armv7/tegra2/clock.c
index 03ac1e3..11d2346 100644
--- a/arch/arm/cpu/armv7/tegra2/clock.c
+++ b/arch/arm/cpu/armv7/tegra2/clock.c
@@ -904,6 +904,20 @@ static int clock_set_rate(enum clock_id clkid, u32 n, u32 m, u32 p, u32 cpcon)
 	return 0;
 }
 
+void clock_ll_start_uart(enum periph_id periph_id)
+{
+	/* Assert UART reset and enable clock */
+	reset_set_enable(periph_id, 1);
+	clock_enable(periph_id);
+	clock_ll_set_source(periph_id, 0); /* UARTx_CLK_SRC = 00, PLLP_OUT0 */
+
+	/* wait for 2us */
+	udelay(2);
+
+	/* De-assert reset to UART */
+	reset_set_enable(periph_id, 0);
+}
+
 int clock_verify(void)
 {
 	struct clk_pll *pll = get_pll(CLOCK_ID_PERIPH);