Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755978Ab3JJRKd (ORCPT ); Thu, 10 Oct 2013 13:10:33 -0400 Received: from mail-pd0-f182.google.com ([209.85.192.182]:45693 "EHLO mail-pd0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755621Ab3JJRKa (ORCPT ); Thu, 10 Oct 2013 13:10:30 -0400 From: Soren Brinkmann To: Rob Herring , Pawel Moll , Mark Rutland , Stephen Warren , Ian Campbell , Rob Landley , Russell King , Mike Turquette , Michal Simek Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, devicetree@vger.kernel.org, Soren Brinkmann Subject: [PATCH v2 1/2] clk/zynq/clkc: Add 'fclk-enable' feature Date: Thu, 10 Oct 2013 10:10:17 -0700 Message-Id: <1381425018-5653-1-git-send-email-soren.brinkmann@xilinx.com> X-Mailer: git-send-email 1.8.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4368 Lines: 111 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 --- v2: - change default value for fclk-enable to '0' --- Documentation/devicetree/bindings/clock/zynq-7000.txt | 4 ++++ drivers/clk/zynq/clkc.c | 18 +++++++++++++++--- 2 files changed, 19 insertions(+), 3 deletions(-) diff --git a/Documentation/devicetree/bindings/clock/zynq-7000.txt b/Documentation/devicetree/bindings/clock/zynq-7000.txt index d99af878f5d7..11fdd146ec83 100644 --- a/Documentation/devicetree/bindings/clock/zynq-7000.txt +++ b/Documentation/devicetree/bindings/clock/zynq-7000.txt @@ -22,6 +22,10 @@ Required properties: Optional properties: - clocks : as described in the clock bindings - clock-names : as described in the clock bindings + - fclk-enable : Bit mask to enable FCLKs in cases no proper CCF compatible + driver is available. Bit [0..3] correspond to FCLK0..FCLK3. The + corresponding FCLK will only be enabled if it is actually + running at boot time. (default = 0xf) Clock inputs: The following strings are optional parameters to the 'clock-names' property in diff --git a/drivers/clk/zynq/clkc.c b/drivers/clk/zynq/clkc.c index 10772aa72e4e..af3bd0aec538 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); -- 1.8.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/