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authorSoren Brinkmann <soren.brinkmann@xilinx.com>2013-11-27 12:16:23 -0800
committerMichal Simek <michal.simek@xilinx.com>2013-12-20 13:23:55 +0100
commitba52f8a986089e263ea28e231b6a405769ae1235 (patch)
treeb2f86681050be4395efc4d5edb51c386d21196cb /drivers/clk/zynq
parent24c039f6acacd63e739b39a030197d5a2945e0d2 (diff)
downloadlinux-ba52f8a986089e263ea28e231b6a405769ae1235.tar.bz2
clk/zynq/clkc: Add 'fclk-enable' feature
In some use cases Zynq's FPGA clocks are used as static clock generators for IP in the FPGA part of the SOC for which no Linux driver exists and would control those clocks. To avoid automatic gating of these clocks in such cases a new property - fclk-enable - is added to the clock controller's DT description to accomodate such use cases. It's value is a bitmask, where a set bit results in enabling the corresponding FCLK through the clkc. FPGA clocks are handled following the rules below: If an FCLK is not enabled by bootloaders, that FCLK will be disabled in Linux. Drivers can enable and control it through the CCF as usual. If an FCLK is enabled by bootloaders AND the corresponding bit in the 'fclk-enable' DT property is set, that FCLK will be enabled by the clkc, resulting in an off by one reference count for that clock. Ensuring it will always be running. Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com> Acked-by: Michal Simek <michal.simek@xilinx.com> Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Diffstat (limited to 'drivers/clk/zynq')
-rw-r--r--drivers/clk/zynq/clkc.c18
1 files changed, 15 insertions, 3 deletions
diff --git a/drivers/clk/zynq/clkc.c b/drivers/clk/zynq/clkc.c
index 10772aa72e4e..09dd0173ea0a 100644
--- a/drivers/clk/zynq/clkc.c
+++ b/drivers/clk/zynq/clkc.c
@@ -102,9 +102,10 @@ static const char *swdt_ext_clk_input_names[] __initdata = {"swdt_ext_clk"};
static void __init zynq_clk_register_fclk(enum zynq_clk fclk,
const char *clk_name, void __iomem *fclk_ctrl_reg,
- const char **parents)
+ const char **parents, int enable)
{
struct clk *clk;
+ u32 enable_reg;
char *mux_name;
char *div0_name;
char *div1_name;
@@ -147,6 +148,12 @@ static void __init zynq_clk_register_fclk(enum zynq_clk fclk,
clks[fclk] = clk_register_gate(NULL, clk_name,
div1_name, CLK_SET_RATE_PARENT, fclk_gate_reg,
0, CLK_GATE_SET_TO_DISABLE, fclk_gate_lock);
+ enable_reg = readl(fclk_gate_reg) & 1;
+ if (enable && !enable_reg) {
+ if (clk_prepare_enable(clks[fclk]))
+ pr_warn("%s: FCLK%u enable failed\n", __func__,
+ fclk - fclk0);
+ }
kfree(mux_name);
kfree(div0_name);
kfree(div1_name);
@@ -213,6 +220,7 @@ static void __init zynq_clk_setup(struct device_node *np)
int ret;
struct clk *clk;
char *clk_name;
+ unsigned int fclk_enable = 0;
const char *clk_output_name[clk_max];
const char *cpu_parents[4];
const char *periph_parents[4];
@@ -238,6 +246,8 @@ static void __init zynq_clk_setup(struct device_node *np)
periph_parents[2] = clk_output_name[armpll];
periph_parents[3] = clk_output_name[ddrpll];
+ of_property_read_u32(np, "fclk-enable", &fclk_enable);
+
/* ps_clk */
ret = of_property_read_u32(np, "ps-clk-frequency", &tmp);
if (ret) {
@@ -340,10 +350,12 @@ static void __init zynq_clk_setup(struct device_node *np)
clk_prepare_enable(clks[dci]);
/* Peripheral clocks */
- for (i = fclk0; i <= fclk3; i++)
+ for (i = fclk0; i <= fclk3; i++) {
+ int enable = !!(fclk_enable & BIT(i - fclk0));
zynq_clk_register_fclk(i, clk_output_name[i],
SLCR_FPGA0_CLK_CTRL + 0x10 * (i - fclk0),
- periph_parents);
+ periph_parents, enable);
+ }
zynq_clk_register_periph_clk(lqspi, 0, clk_output_name[lqspi], NULL,
SLCR_LQSPI_CLK_CTRL, periph_parents, 0);